The pick and roll is often employed by a shorter guard handling the ball and a taller forward or center setting the screen; if the taller defender switches to guard the ballhandler, then the offensive team can have favorable mismatches. The shorter guard has a speed advantage over the taller defender, while the taller forward/center has a size advantage over the shorter defender.


A successful pick and roll play may result in the screener being in position to receive a pass with a clear path for an easy shot, with the chance of drawing a foul as other defenders move toward the play to try to prevent penetration. It may alternately lead to the ballhandler being momentarily without a defender, and thus free to pass to any open teammate, or take an uncontested shot, which greatly improves the chance of scoring, again with the chance of drawing a foul as the screened defender hurries to get back into the play.


The success of the strategy depends largely on the ballhandler, who must recognize the situation quickly and make a decision whether to take the shot, pass to the screener who is rolling (if the defender switches) or pass to another open teammate (if other defenders come to help). The screener also must recognize the open spaces of the court to roll to and be alert to receive the pass and finish the play.


Variations of the pick and roll are the "pick and pop" (or "pick and fade"), where the screener moves for an open jump shot instead of rolling to the basket, or the "pick and slip", where the screener fakes setting a screen before slipping behind the defender to accept the pass.


The pick and pop is an offensive play that is a derivative of the classic pick and roll. Instead of rolling toward the basket, however, the player setting the pick moves ("pops") to an open area of the court to receive a pass from the ballhandler for a jump shot.


The premise of the two plays is the same: a ballhandler uses a teammate's pick to attract the attention of two defensive players to free his teammate for a scoring opportunity. A successful pick and pop relies on a ballhandler who demands constant defensive attention and a teammate with an accurate jumpshot or a layup if by the rim.


According to Synergy Sports Technology, use of the pick and roll in the NBA rose from 15.6% of total plays in the 2004–05 NBA season to 18.6% in the 2008–09 NBA season.


The pick and roll is also used extensively in box lacrosse, the sport played in the National Lacrosse League.


Nellie Ball is an offensive strategy in basketball developed by NBA head coach Don "Nellie" Nelson. It is a fast-paced run-and-gun offense relying on smaller, more athletic players who can create mismatches by outrunning their opponents. A true center is usually not needed to run this type of offense. A large volume of three-point attempts is also a feature of Nellie Ball. This offense is most effective against teams that do not have the athleticism or shooting ability to keep up with the fast pace.


While coaching the Dallas Mavericks, Nelson employed Nellie Ball once again, utilizing the All-Star trio of Steve Nash, Michael Finley, and Dirk Nowitzki. Nelson often played Nowitzki, a natural power forward, at the center position, placing him at the three-point line in order to stretch out the defense. Nelson's trio of star players spearheaded the Mavericks' transformation into a promising young franchise capable of reaching the NBA Playoffs.


Avery Johnson, Nelson's protégé and successor in Dallas, had abandoned Nellie Ball in favor of a more traditional offensive lineup, which reached the 2006 NBA Finals. En route to reaching the finals, Johnson's Mavericks defeated Mike D'Antoni's Phoenix Suns, the latter using an up-tempo style centered on former Mavs superstar and 2-time NBA MVP Steve Nash. Although the Mavericks lost to the Miami Heat in the NBA Finals that year, Johnson won the 2006 NBA Coach of the Year Award for making Dallas a better defensive team while still keeping their up-tempo style of offense.


Further validation of the Nellie Ball formula was served when the Golden State Warriors, a team Nelson had coached twice, won the 2015 NBA Championship. The Warriors, who were now led by head coach Steve Kerr, successfully closed out the 2015 NBA Finals against the Cleveland Cavaliers using a Nellie Ball-style "Death Lineup" of Stephen Curry, Klay Thompson, Andre Iguodala, Harrison Barnes and Draymond Green. In 2017 & 2018, Golden State won back-to-back NBA titles. This time, the high-scoring Warriors were powered by Curry, Thompson, Green, and fellow superstar Kevin Durant. Additionally, multiple teams have adopted different variations of Nellie Ball, with point forwards orchestrating some of the most prolific offenses in the current NBA.


The Princeton offense is an offensive basketball strategy which emphasizes constant motion, back-door cuts, picks on and off the ball, and disciplined teamwork. It was used and perfected at Princeton University by Pete Carril, though its roots may be traced back to Franklin “Cappy” Cappon, who coached Princeton in the late 1930s, and Bernard "Red" Sarachek, who coached at Yeshiva University from 1938 to 1977.


The offense is designed for a unit of five players who can each pass, shoot, and dribble at an above-average level. These players hope to isolate and exploit a mismatch using these skills. Positions become less important and on offense there is no point guard, shooting guard, small forward or power forward. However, there are certain rules that players running this offense are expected to follow.


The offense usually starts out with four players outside the three-point arc with one player at the top of the key. The ball is kept in constant motion through passing until either a mismatch allows a player to cut to the basket or a player without the ball cuts toward the unoccupied area under and around the basket, and is passed the ball for a layup. The post player is a very important player in the offense. He sets up in the high post and draws attention to his positioning. When the ball is received in to the post the players main objective is to find back door cutters or defenders who have fallen asleep on the weak side.


The hallmark of the offense is the backdoor pass, where a player on the wing suddenly moves in towards the basket, receives a bounce pass from a guard on the perimeter, and (if done correctly) finds himself with no defenders between him and a layup. Alternatively, when the defensive team attempts to pack the paint to prevent backdoor cuts, the offense utilizes three point shots from the perimeter. All five players in the offense—including the center—should be competent at making a three-point attempt, further spreading the floor, and not allowing the defense to leave any player unattended.


The offense is often a very slowly developing one, relying on a high number of passes, and is often used in college basketball by teams facing opponents with superior athletic talent in order to maintain a low-scoring game (believing that a high-scoring game would favor the athletically superior opponent). As a result, Princeton has led the nation in scoring defense 19 times including in every year from 1989 to 2000.


During his tenure as head coach of Princeton (1967–1996), Pete Carril compiled a 514–261 record, a .658 winning percentage. His teams won 13 Ivy League championships during his 29-year tenure with the Tigers, and received 11 NCAA Tournament bids and two National Invitation Tournament berths. Princeton captured the NIT title in 1975. Perhaps Carril's greatest win was his final upset victory on a backdoor cut to give Princeton the win 43 - 41 over the 1995 defending NCAA champion UCLA. The win extended Coach Carril's retirement by one game and is ranked as one of the best NCAA upsets of all time. Former Princeton coach Sydney Johnson and his predecessors Bill Carmody, John Thompson III, and Joe Scott have all employed the Princeton offense.


After his retirement from Princeton in 1996, Pete Carril served as an assistant coach for the National Basketball Association's Sacramento Kings until 2006. During his time with Sacramento, Carril helped Rick Adelman, who became the Kings' head coach in 1998, implement the Princeton offense. Carril returned to the Kings during the 2008–2009 season as a consultant.


The Cleveland Cavaliers, Los Angeles Lakers, New Orleans Hornets, New Jersey Nets, and Washington Wizards also have run versions of the Princeton offense. in the National Basketball Association. Rick Adelman introduced a modified version of Pete Carril's system to the Houston Rockets during the 2007–2008 season. Coach Alvin Gentry also implemented an altered version of it that shows similarities to the triangle offense during the Phoenix Suns′s 2012–13 season. Eddie Jordan implemented the Princeton offense as coach of the Washington Wizards from 2003 to 2008) and of the Philadelphia 76ers from 2009 to 2010.


Besides Princeton, some of the NCAA Division I college basketball teams best known for using the offense are:


NCAA Division II colleges that have used the Princeton offense include:


NCAA Division III colleges that have used the Princeton offense include:


NAIA colleges that have used the Princeton offense include:


High school basketball teams that have used the Princeton offense include:


Amateur Athletic Union, Youth Basketball of America, and United States Basketball Association teams that have used the Princeton offense include:


Hack-a-Shaq is a basketball defensive strategy used in the National Basketball Association (NBA), where Dallas Mavericks coach Don Nelson adapted the strategy of committing intentional fouls (originally a clock management strategy) to the purpose of lowering opponents' scoring. He directed players to commit personal fouls throughout the game against selected opponents who shot free throws poorly.


Nelson initially used the strategy against Dennis Rodman, a star power forward for the Detroit Pistons, San Antonio Spurs, and Chicago Bulls. However, the strategy acquired its name for Nelson's subsequent use of it against Hall of Fame center Shaquille O'Neal.


The term was coined when O'Neal played at LSU and during his NBA tenure with the Orlando Magic. At that time, the term referred simply to especially physical defense against O'Neal. Teams sometimes defended him by bumping, striking or pushing him "after" he received the ball to deny him an easy layup or slam dunk. Because of O'Neal's poor free throw shooting, teams did not fear the consequences of committing personal fouls. However, once Nelson's off-the-ball fouling strategy became prevalent, the term "Hack-a-Shaq" was applied to this new tactic, and the original usage was largely forgotten.


The name is sometimes altered to reflect the player being fouled, for example "Hack-a-Howard" when used against Dwight Howard, or "Hack-a-DJ" for DeAndre Jordan.


Committing repeated intentional personal fouls is a longstanding defensive strategy used by teams that are trailing near the end of the game. Basketball, unique among major world sports, permits intentional fouling to gain a strategic advantage; in other sports, it is considered an unfair act or professional foul.


Once the fouling team enters the penalty situation, the fouled team is awarded free throws. The typical NBA player makes a high enough percentage of his free throws that, over time, opponents' possessions that end with free throws will yield more points than possessions in which the opponents try to score a field goal. Even the highest-scoring NBA teams average only about 1.1 points per possession. Giving such a team two free throws on each possession, the poorest free throw shooting teams make around 70% of their free throws and would score 1.4 points per possession. So intentionally fouling tends not to reduce the opponent's score.


However, fouls stop the game clock. If a team is trailing with time running out, intentional fouling may be the only hope. In normal game play, the opponents will stall and run out the clock, even at the expense of failing to score, to the extent that the shot clock allows. The trailing team fouls intentionally to end the opponents' possession as soon as possible, leaving more time on the clock for the opposing team to respond to any score. It may also hope that fatigue and pressure affect the ability of the free-throw shooter.


When this strategy was originally employed in the NBA, the trailing team often made a point of fouling the opposition player who was the poorest free throw shooter in the game at that time, even if that player did not possess the ball. However, fouling "off the ball" became a problem for the league when Wilt Chamberlain—a player of superstar caliber but an atrocious free throw shooter—entered the NBA.


Wilt Chamberlain and the off-the-ball foul rule.


Wilt Chamberlain was such a dominant player that he was sure to be on the floor near the end of any close game. However, he was such a poor free throw shooter (51%) as to be the natural target of a strategy of intentional fouling. The opposition was eager to send Chamberlain to the free throw line, and Chamberlain wished to avoid doing so. This led to a game of tag developing away from the basketball, players chasing Chamberlain as he tried to avoid being fouled.


The NBA enacted a new rule on off-the-ball fouls—personal fouls against an offensive player who neither has the ball nor is trying to obtain it. On such fouls within the last two minutes of the game or in overtime, the offensive team is awarded the usual number of free throws and then possession of the ball. The new rule removed the benefit of fouling to gain possession of the ball and limited late-game intentional fouls to the ball handler.


The current version of the rule contains an additional disincentive to off-the-ball fouls: The free throws need not be attempted by the player who was fouled; the fouled team can choose as shooter any player on the court at the time.


The reason they have that rule is that fouling someone off-the-ball looks foolish . . . Some of the funniest things I ever saw were players that used to chase [Wilt Chamberlain] like it was hide-and-seek. Wilt would run away from people, and the league changed the rule based on how silly that looked.


There are several late-game situations where committing an isolated intentional foul makes sense. For a team trailing, late in the game, stopping the clock is a higher priority than keeping the opponents from scoring. In other situations, intentional fouling does not make sense because it typically lets the opponents score more points.


Intentional fouling every time the opponents get the ball was an innovation of Don Nelson in the late 1990s as coach of the Dallas Mavericks. He theorized that, if the opponents played an especially bad free throw shooter, intentionally fouling him might hold down his team's points per possession, compared to a conventional defense against them. Nelson used the strategy throughout the game, when the late-game penalties for off-the-ball fouls did not apply, such as the ball being given back to the fouled team.


Nelson did not invent the strategy; his innovation was to take a strategy whose primary purpose had always been simply stopping the clock, and use it instead primarily to minimize the opposition's scoring.


Nelson first used the strategy against Dennis Rodman of the Chicago Bulls in 1997, who was making 38% of his free throws on the season. He could not use the strategy on every Bulls possession, as a player committing his sixth foul is disqualified from the game. He used the strategy selectively, and chose a little-used player, whose absence the team could tolerate, to commit the fouls. He believed that Rodman's horrific foul shooting would result in the Mavericks actually giving up fewer total points during those Bulls possessions than they would give up by playing a standard defense against the Bulls' efficient offense, led by Michael Jordan and Scottie Pippen.


In that game, Rodman shot 9-for-12 from the free throw line, defeating the strategy, and the Bulls won the game. The strategy was thus largely forgotten, except that Maverick player Bubba Wells, who had been assigned to foul Rodman, set the all-time NBA record for fewest minutes played (3) before fouling out of a game.


Nelson used the strategy again in 1999, this time against Shaquille O'Neal, a career 52% free throw shooter. Other NBA coaches also did so to defend against O'Neal. So, even though it had been first used two years earlier against Rodman, the strategy became known for its use against O'Neal.


As with Chamberlain decades earlier, intentional off-the-ball fouls against O'Neal became controversial. During the 2000 NBA Playoffs, both the Portland Trail Blazers and Indiana Pacers relentlessly used the Hack-a-Shaq defense against the Lakers. The NBA discussed expanding the off-the-ball foul rule to cover more than just the final two minutes of the game, or another rule change that would discourage the use of Hack-a-Shaq. Ultimately, though, the NBA did not change any rules to discourage the Hack-a-Shaq strategy. An effective rebuttal was that the Lakers won both of the games where Hack-a-Shaq was notorious, suggesting that the strategy was too ineffective to require remediation.


In subsequent seasons, fans and media remained displeased with the continued use of the strategy, particularly in high-profile playoff games. In 2008, the NBA Competition Committee again considered rule changes but did not achieve consensus. According to an ESPN study in 2016, offensive efficiency was higher than the Golden State Warriors when the Hack-a-Shaq strategy was used against a team. NBA commissioner Adam Silver announced that the competition committee would look into changing the rule before the start of the 2016–2017 season due to extended length of games. It takes only three or more Hack-a-Shaq fouls to add 11 minutes to the length of a game, and at the time such fouls were being committed at a rate of four times more often than the prior season.


The Hack-a-Shaq strategy is most effective against a player who shoots free throws poorly, but who is so effective in other areas that the coach is reluctant to simply remove them from the game. Few players other than O'Neal meet those criteria.


Ben Wallace shot only 42% free throws over his career, the worst percentage in the history of the NBA among players with 1000 attempts. Bruce Bowen was also among the game's best defenders but among its worst free throw shooters. Because of their struggles at the free throw line, each man has at times become a target of the Hack-a-Shaq strategy.


On May 29, 2012, the Oklahoma City Thunder used a so-called hack-a-Splitter strategy on Tiago Splitter during Game 2 of Western Conference Final of 2012 NBA Playoffs, who made 5 of 10 free throw attempts from these fouls.


On April 10, 2015, the San Antonio Spurs was reported to use this strategy on Josh Smith to keep the basketball away from the super-hot James Harden and San Antonio Spurs won this season game by 104–103.


During the 2015 NBA Playoffs, Howard, then with the Houston Rockets, was again targeted often by opponents, particularly during round 2 against the Los Angeles Clippers. During Game 2, Howard shot 21 (converting 8) out of the 64 free throws for the Rockets. In turn, the Rockets targeted DeAndre Jordan, who had been victim of "Hack-a-Jordan" or "Hack-a-DJ" since 2014, and in particular was fouled five times in two minutes during the previous playoff round against the San Antonio Spurs. In Game 4, Jordan broke O'Neal's record for most free throw attempts in a half game with 28.


On January 20, 2016, the Houston Rockets used Hack-a-Drummond against Detroit Pistons center Andre Drummond, and Drummond went 13 for 36 from the free throw line. Those 23 misses are an NBA record for most free throws missed by a player in a game. However, the Pistons would still win the game 123-114.


In the 2016–17 playoffs, Oklahoma City Thunder forward André Roberson was a victim of this strategy against the Houston Rockets in the first round of the playoffs. Roberson shot 3/21 in the series.


On November 29, 2017, the Washington Wizards used what a newspaper called a "hack-a-Ben Simmons strategy" when trailing the Philadelphia 76ers by 24 points in the third quarter. The Wizards repeatedly fouled 76ers point guard Ben Simmons, giving him 29 free throws, 24 of them in the fourth quarter. Simmons was a notoriously bad shooter and had entered the game with a 56% free throw rate. He shot free throws even worse in this game, making 15/29 (52%). However, the 76ers held on to win the game, 118-113. Simmons' 31 points were a career high for him at the time.


Detractors argue that deliberate fouling makes the game unpleasant to watch, violates the spirit or disrupts the rhythm of the game, puts the fouling team too quickly into the penalty situation, and disparages the team's defensive abilities.


"All that did was allow us to set our defense. I think that's disrespectful to their players. Basically, they were telling their players that they couldn't guard us."


Many coaches have heeded these criticisms and doubted the effectiveness of the strategy in minimizing scoring. One imponderable is the effect on the psychology of the player fouled deliberately on the belief that he will not make his free throws. Some believe that frequently sending O'Neal to the foul line risked putting him "into a rhythm" and temporarily making him a better shooter.


These factors, and the fact that there are only handful of players who satisfy the criteria for Hack-a-Shaq, mean that the strategy is uncommon in the NBA. A rule change starting in the 2016–17 NBA season put an additional constraint on deliberate fouling: Away-from-the-ball fouls now award the fouled team a free throw and possession of the ball in the final 2 minutes of "each" quarter, extended from the prior rule affecting only the final 2 minutes of the 4th quarter. The rule change sought to eliminate cases where teams would intentionally foul off-the-ball in order to gain the final possession of a quarter.


In basketball, run and gun is a fast, freewheeling style of play that features a high number of field goal attempts, resulting in high-scoring games. The offense typically relies on fast breaks while placing less emphasis on set plays. A run-and-gun team typically allows many points on defense as well.


In the National Basketball Association (NBA), the run and gun was at its peak in the 1960s when teams scored an average of 115 points a game. Around 2003, the average had dropped to 95. The Boston Celtics were a run-and-gun team in the 1950s and 1960s while winning 11 NBA championships, as were the five-time champion Los Angeles Lakers during their Showtime era in the 1980s.


Although the run and gun is believed by many to de-emphasize defense, the Celtics of the 60s' had Bill Russell, and the Lakers of the 80s' had Kareem Abdul-Jabbar as defensive stoppers. Coach Doug Moe, who ran the run and gun with the Denver Nuggets in the 1980s, believed the high scores surrendered were more indicative of the fast pace of the game than a low level of defense. Still, his teams sometimes appeared to give up baskets in order to score one. Though his offensive strategy led to high scores, Moe's Denver teams were never adept at running fast breaks.


Paul Westhead coached the Loyola Marymount men's basketball team in the late 1980s using a version of the run and gun.


While run and gun basketball is often thought of as a system of offense, Westhead's system uses a combined offensive and defensive philosophy. Offensively, the team moves the ball forward as quickly as possible and takes the first available shot, often a three-pointer. Westhead's teams try to shoot the ball in less than seven seconds. The aim is to shoot before the defense is able to get set. Defensively, the team applies constant full-court pressure. Generally, the team is willing to gamble on giving away easy baskets for the sake of maintaining a high tempo.


Loyola Marymount successfully used the system in 1990 when they advanced to the Elite 8 of the NCAA Basketball Tournament, beating the defending champion Michigan 149–115 along the way. The style has been used at some other teams. Coach Westhead tried, rather unsuccessfully, to implement the system in the NBA with the Denver Nuggets in the early 1990s. They averaged a league-best 119.9 points per game in 1990-91, but also surrendered an NBA record 130.8 points per game. They also allowed 107 points to be scored in a single half to the Phoenix Suns, which also remains an NBA record.


Westhead's system has been imitated by other college teams, including Grinnell College. David Arseneault, the architect of the Grinnell System, added to Westhead's system by substituting players in three waves of five players, similar to an ice hockey shift. The highest scoring game in NCAA history was played by two teams (Troy & DeVry-Atlanta) who both employed Westhead's system the entire game, resulting in 399 combined points in 1992.


The Grinnell System, sometimes referred to as The System, is a fast-tempo style of basketball developed by coach David Arseneault at Grinnell College. It is a variation of the run-and-gun system popularized by coach Paul Westhead at Loyola Marymount University in the early 1980s. The Grinnell System relies on shooting three-point field goals, applying constant pressure with a full-court press, and substituting players frequently.


Under the system, Grinnell guard Jack Taylor scored an NCAA-record 138 points in a 2012 game, and 109 in a 2013 game. Previously, Grinnell players Jeff Clement (77) and Griffin Lentsch (89) held the Division III scoring record.


The main tenets of the system are:


To keep his players fresh and get more individuals involved, Arseneault added to Westhead's system by substituting players in three waves of five players, similar to an ice hockey shift. A 15-man roster is divided three groups of five and new shifts are substituted every 45 to 90 seconds. Each shift plays at full speed and then rests while the next group does the same. Players rarely play more than 20 minutes a game.


Arseneault and the Grinnell program have been criticized for using the system to run up the score and set records, especially against overmatched opponents.


Other college and high school programs have also adopted the Grinnell System. David Arseneault Jr., the coach's son, ran a modified version of The System after being named the head coach of the Reno Bighorns of the NBA Development League in 2014–15. Limited to a 10-man roster and subject to the D-League's high roster turnover, Arseneault adjusted the system, abandoning its hockey-style substitutions and full-court press.


The M-drop is a play in the sport of water polo which is mainly used when there is a strong, offensive set of players. The defense sets up in an M-shape, hence the name "M-Drop".


A basic offense would look like an umbrella shape, with 5 offensive players in a half-circle around the goal, with one defensive player on each of them. There is one player in the middle, called set. There is one defensive player guarding each of the offensive players. From left to right, and moving around the circle, the offensive players are named 1, 2, 3, 4, 5, and the set is 6. The defensive players are named D1, D2, D3, D4, D5, and D6, who guard sets.


If the opposing team has a very strong set player, the D3 player will drop back and help the D6 player. This play leaves the offensive player 3 open, so defensive members D2 and D4 will “split” while swimming in between their player and offensive player 3. They also split in between the set and their player, hence the name M-drop, from the ‘M’ shape created.


In water polo, the goalkeeper occupies a position as the last line of defense between the opponent's offence and their own team's goal, which is .


The goalkeeper is different from other people on their team; they possess certain privileges and are subject to different restrictions from those of field players. As well as this, they must possess different skills from those of the fielders.


Goalkeepers often have longer playing careers than field players because they swim far less.


In water polo, the goalkeeper is commonly known as the "goalie" or "keeper" and may also be known as "the man/woman in the cage".


The position of the goalkeeper has existed since the game of water polo originated. At that time, the object of the game was to touch the ball on the opponent's end of the pool. The goalkeeper would wait at the end of the pool until an opposing player approached the goal, when the goalkeeper would try to stop that player, for example, by dunking their head.


A change occurred in the game and the role of the goalkeeper in the 1880s, when the Scottish reduced the size of the scoring area by placing rugby posts, spaced about 10 feet apart, at each end of the pool. At the same time, the rules were changed to allow goalkeepers to stand on the pool deck and leap onto the head of an opposing player who approached the goal. This change in the rules was brief. To prevent the serious injuries that resulted from this method of goalkeeping, the rules were revised again to require the goalie to remain in the water.


The basic functions of the goalie position have changed little over the last century, but there have been changes affecting the style of play. In the 1940s, Hungary introduced a new technique called the eggbeater kick that enables goalkeepers to maintain a stable balance in the water.


Inside the area, the goalkeeper is the only person on the team permitted to touch the ball with two hands, touch the bottom of the pool and punch the ball with a clenched fist. Although the goalkeeper may not advance beyond the half-way line, they may attempt shots at the other goal.


Any goalkeeper who aggressively fouls an attacker in position to score can be charged with a penalty shot for the other team. The goalkeeper can also be temporarily ejected from the game for twenty seconds if they prevent a likely goal (for example, by splashing). If the goalkeeper pushes the ball under the water in the area, instead of being a free throw to the other team, it is a penalty. A penalty is also awarded to the other team if the goalkeeper pulls down from the crossbar of the goal to prevent a goal.


Unless reserve, all goalkeepers caps are numbered 1 and contrast with their team's colour to distinguish their position. Reserve goalkeepers have differently numbered caps depending on the governing body; they are shown in the table below.


Below is a table showing the major differences of rules and regulations for water polo goalkeepers between the three largest governing bodies: FINA, NCAA and NFHS.


In water polo, field players possess entirely different skills and responsibilities to the goalkeeper.


The primary role of the goalkeeper is to block shots at the goal. After saving the ball, the goalkeeper has the responsibility to keep possession of the ball in order to stop opposing players regaining possession. They must make sure that whenever the opposition appears to be ready to make a shot on goal, their hands are near or above the surface of the water. They also possess the job to pass down the pool accurately in order to retain possession of the ball, often starting the team's counterattack.


The goalkeeper is the only player who may block a penalty and because 63.7% of penalties are goals, the goalkeeper has a massive role in this area but failure to be in the correct position at a penalty is an exclusion foul. At a penalty shootout, the goalkeeper's job is critical and will largely determine the outcome of the match. If the goalkeeper is excluded during the course of the penalty shootout, then one of the other five players in the pool may take their place. The goalkeeper's hips should be high at a penalty shot to give them extra height. The goalkeeper should do one of two things at a penalty shot:


Moreover, goalkeepers should have leadership. They should inform field players of information, such as unmarked players and the time of the game clock and give instructions to the field players. Because of this, they may sometimes be known as "the coach in the water".


When a man down, goalkeepers have extra responsibility. It is easier for the other team to continue to shoot, making the goalkeeper very worn out. Platanou said that with a man down the goalkeeper had "The highest possible intensity".


Most of the time, goalkeepers do low-intensity work (treading water without too much effort) but when they do work (for example, when they have a man down or are in the ready position) it is very intense.


Goalkeepers must be able to perform the eggbeater kick to a high standard. Before the eggbeater kick, goalkeepers would use breaststroke which meant that they could not stay up for very long and players found it easier to score. By using the eggbeater kick, goalkeepers can raise their bodies high enough in the water to be able to block shots at the goal for longer periods of time. This can be used conjunctively with sculling, in which the goalkeeper keeps their hands closed (with the fingers together) and moves them forwards and backwards.


The easiest way for the goalkeeper to block shots is for them to block the ball with either their hands or arms. Longer arms can help the goalkeeper to reach the ball, thus being an advantage. Sports involving quick reactions may be helpful, as these help the goalkeeper's reflexes which is a crucial skill.


In order to improve, there are a variety of drills designed to improve the goalkeeper's skill.


To start with, there are drills to help improve the goalkeeper in the water. These range from simple exercise (such as jumping as high out of the water as possible with two hands) to drills not specifically used in water polo; rather they are used to improve the goalkeeper's core muscles (such as catching a ball dropped from the side into the water).


As the goalkeeper must be able to swim quickly for short distances, to improve they can practice exercises such as swimming quickly and then immediately stopping without touching the sides. It is important for the goalkeeper to swim both breastroke and freestyle - the breastroke helping with the eggbeater kick and the freestyle helping with the swimming in the match.


Moreover, at the start of the game it is vital for the goalkeeper to stretch for 15 minutes.


As blocking the ball is the primary role of the goalkeeper, they must have good knowledge of blocking techniques.


As the goalkeeper has the choice of how many hands they want to use, the decision should be made of what they want to do. A shot should be stopped with two hands either if it is weak or close to the goalkeeper's body, and normally stopped with one in other circumstances. This is because one-handed saves can go to the ball faster.


Most shots are saved with the arms or the hands, but goalkeepers are known to save shots with their faces and even feet.


Hole set is an offensive position in the game of water polo. It can be referred to as either just the "hole" position or the "set." Because this player is typically positioned on the two meter (2M) marker and in center of the opposing team's goal, the position can also be called the two-meter or simply 2M. Other names for this position include center forward, due to the similarity between the corresponding basketball position, as well as the pit-man. The defensive player guarding the hole set can be called the hole-D, where D stands for defense, two-meter defender, or 2M-D.


Track and field racers have a variety of options in the ways they can choose to pace their races.


Even-splitting is a strategy in which the racer attempts to hit the same split in every lap of the race. The racer tries to run an "even" pace during the entire race. In long-distance events, this can often be an optimal strategy.


Positive-splitting is a racing strategy that involves completing the first half of a race faster than the second half. Typically, the runner goes out at a pace faster than he or she can maintain for the entire race, leading to a slower end of the race. Positive-splitting can be employed as a tactic, or can simply be a byproduct of an overambitious early pace.


Negative-splitting is a racing strategy that involves completing the second half of a race faster than the first half. The racer runs slow in the beginning, and gradually runs faster as the race progresses. This is typically seen as a conservative racing strategy, but in distance events, many world records have been run with a slight negative split.


Sit-and-kick, a related strategy to negative-splitting, is one in which the racer typically sits in the pack of the race, not taking the lead or going very fast, and then attempts to "kick" or sprint by the other racers during the last laps of the race. The sit-and-kick can be employed by individual runners or, in the case of many championship races, the entire field may attempt to sit-and-kick, thus leading to drastically slow times for the first few laps and faster than normal times for the last laps.


While all of the above strategies can be employed, certain pacing strategies, for physiological reasons, will yield the fastest times.


For the 100m and 200m events, pacing is not a factor. Because the race is so short, racers simply run at their top speed for the duration of the race. However, for the 400m at the elite level, the event is almost uniformly run with a positive-split strategy. Runners run the first 200m faster than the final 200m.


In the 800 meters, the fastest times have almost always been achieved with a positive-split strategy. A study of 26 world-record 800m races from 1912 to 1997 showed that in 92% of the fastest 800m races, the first half of the race has been run faster than the second half. This implies that the optimal strategy for the 800m is to positive-split.


In the 400 meters, the strategy proven to be the most effective is starting off at a 70-75% pace and working up to 100%, or known as the threshold pace strategy. Examples of this race plan are Michael Johnson’s former World Record of 43.18 in 1999 and Cathy Freeman’s Olympic Gold Medal in 2000, both 400 meters runners who benefited from this type of pacing strategy.


In the 5000 meters and 10000 meters, the optimal strategy shifts to even-splitting. An analysis of world-record performances in these events shows a clear pattern: relatively even pacing throughout most of the race, and a slight increase in speed in the last 1000m of both the 5000m and 10000m. While one could interpret this concluding increase in speed as evidence of a sit-and-kick strategy, the increase in speed observed in these performances is not nearly as dramatic and pronounced as what is typically observed in a sit-and-kick type race.


Although "swindling" in general usage is synonymous with cheating or fraud, in chess the term does not imply that the swindler has done anything unethical or unsportsmanlike. There is nonetheless a faint stigma attached to swindles, since players feel that one who has outplayed one's opponent for almost the entire game "is 'morally' entitled to victory" and a swindle is thus regarded as "rob[bing] the opponent of a well-earned victory". However, the best swindles can be quite artistic, and some are widely known.


There are ways that a player can maximize their chances of pulling off a swindle, including playing actively and exploiting . Although swindles can be effected in many different ways, themes such as stalemate, perpetual check, and surprise mating attacks are often seen.


The ability to swindle one's way out of a lost position is a useful skill for any chess player and according to Graham Burgess is "a major facet of practical chess". Frank Marshall may be the only top player who has become well known as a frequent swindler. Marshall was proud of his reputation for swindles, and in 1914 wrote a book entitled "Marshall's Chess "Swindles"".


Frank Marshall, a gifted who was one of the world's strongest players in the early 20th century, has been called "the most renowned of swindlers". To Marshall, the term 'swindle' "meant a particularly imaginative method of rescuing a difficult, if not lost, position." The phrase "Marshall swindle" was coined because Marshall "was famed for extricating himself from hopeless positions by such means".


Perhaps the most celebrated of his many "Marshall swindles" occurred in Marshall–Marco, Monte Carlo 1904. Marshall wrote of the position in the leftmost diagram, "White's position has become desperate, as the hostile b-pawn must queen." White could play 45.Rxc7+, but Black would simply respond 45...Kb8, winning. Many players would resign here, but Marshall saw an opportunity for "a last 'swindle. He continued 45.c6 Now Black could have played 45...bxc6!, but disdained it because White could then play 46.Rxc7+ Kb8 47.Rb7+! Kxb7 48.Nc5+, winning Black's rook and temporarily stopping Black's pawn from advancing.


Black should have played this line, however, because he still wins after 48...Ka7 49.Nxa4: while there are many ways to win from the resulting position, the quickest would be to play Bd4, trapping the knight, and after 50.Kf3 Ka6 51.Ke4 Ka5 52.Kxd4 Kxa4 53.Kc3 Ka3, Black's pawn queens after all. Instead, Marco played 45...Be5, mistakenly thinking that this would put an end to Marshall's tricks. The game continued 46.cxb7+ Kb8 (46...Kxb7? 47.Nc5+ wins the rook) 47.Nc5! Ra2+ 48.Kh3 b2 49.Re7! Ka7 (not 49...b1=Q 50.Re8+ Ka7 51.Ra8+ Kb6 52.b8=Q+, winning Black's newly created queen) 50.Re8 c6 51.Ra8+ Kb6 52.Rxa2! b1=Q (rightmost diagram).


White's resources finally seem to be at an end, but now Marshall reveals his deeply hidden point: 53.b8=Q+ Bxb8 54.Rb2+! Qxb2 55.Na4+ Kb5 56.Nxb2. Marshall has caught Black's pawn after all, and is now a pawn up in a position where it is Black who is fighting for a draw. Fred Reinfeld and Irving Chernev commented, "Marshall's manner of extricating himself from his difficulties is reminiscent of an end-game by Rinck or Troitsky!" Marshall eventually won the game after a further mistake by Black.


International Master (IM) Simon Webb in his book "Chess for Tigers" identified five "secrets of swindling":


Grandmaster (GM) John Nunn adds a caveat: when in a bad position, one must decide between two strategies, which he calls "grim " and "create confusion." "Grim defence" involves finding some way to hang on, often by liquidating to an ending. "Create confusion" entails trying to "gain the initiative, even at material cost, hoping to stir up complications and cause the opponent to go wrong." Nunn cautions that, "If you decide to go for 'create confusion' then you should press the panic button sufficiently early to give yourself a reasonable chance of success. However, you should be sure that your position is really bad enough to warrant such drastic measures. In my experience, it is far more common to panic too early than too late."


Negi also notes that the prospective swindler should "keep enough options on the board so your opponent has a chance to see ghosts and lose his bearings. The closer he gets to winning, the less he wants to work – exploit that state of mind!"


Such play-acting can be carried to extremes. GM Nikolai Krogius writes that Najdorf, in his game against Gligorić at the 1952 Helsinki Olympiad, "left a pawn "" in time trouble, and then desperately clutched his head and reached out as if wanting to take the pawn back. ... Gligorić took the pawn, and soon thereafter lost the game. It transpired that Najdorf had staged the whole pantomime to blunt his opponent's watchfulness. This can hardly be called ethical."


Swindles can occur in myriad different ways, but as illustrated below certain themes are often seen.


One classic way of saving a draw in a losing position is by stalemate. Almost every master has at some point spoiled a won game by falling into a stalemate trap. The defender often achieves the stalemate by sacrificing all of his or her remaining mobile pieces, with check, in such a way that they must be captured, leaving the defender with only a king (and sometimes also pawns and/or pieces) with no legal moves.


Another well-known Marshall swindle is Marshall–MacClure, New York 1923 (diagram at above left). Marshall, a rook down, played 1.Rh6! Rxh6 2.h8=Q+! Rxh8 3.b5! A very unusual position has arisen: now Black is up "two" rooks and on move, but the only way to avoid stalemate is 3...Rd7 4.cxd7 (threatening 5.d8=Q+, forcing stalemate) c5?? 5.bxc6 Kb8 6.Kxb6, when White even wins. Decades later, someone pointed out an alternative draw with 1.Rg6! fxg6 2.h8=Q+ Rxh8 3.b5 or 1...Re8 2.Rg8 Rb8 3.b5.


In Chigorin–Schlechter, Ostend 1905, (diagram at above right), a game between two of the leading players of the day, an unusual combination of stalemate and "zugzwang" enabled the great Schlechter to rescue a desperate position. Schlechter, in extreme , played 44...Qc7+! Chigorin, thinking Schlechter had blundered, responded 45.Qb6+??, seemingly forcing the trade of queens. Schlechter's 45...Ka8! forced an immediate draw: 46.Qxc7 is stalemate, and 46.Ka6 Qc8+! 47.Ka5 allows a draw with either 47...Qc7! ("zugzwang"), when White cannot make progress, or 47...Qc3+! 48.Ka6 Qc8+! with a perpetual check.


In Kasparov–McDonald, simultaneous exhibition, Great Britain 1986, (left-most diagram), the world champion had a winning advantage, which he could have converted with 54.Qd6+ Kg7 55.c6! Instead, he played 54.Bxe4??, allowing 54...Rxg3+! 55.Kxg3 Qe5+! , since the forced 56.Qxe5 gives stalemate (right-most diagram). Note that 55.Kh4 (instead of 55.Kxg3), with the strong threat of 56.Qh7#, would have been met by 55...Rg4+! 56.Kxg4 (forced) Qd7+! 57.Qxd7 with a different stalemate.


For further examples of swindles based on stalemate, see Stalemate; Desperado (chess); Congdon–Delmar, New York 1880; Post–Nimzowitsch, Barmen Masters 1905; Schlechter–Wolf, Nuremberg 1906; Znosko-Borovsky–Salwe, Ostend B 1907; Walter–Nagy, Győr 1924; Janowski–Grünfeld, Marienbad 1925; Heinicke–Rellstab, German Championship 1939; Bernstein–Smyslov, Groningen 1946; Horowitz–Pavey, U.S. Championship 1951; Fichtl–F. Blatny, Czechoslovakia 1956; Portisch–Lengyel, Málaga 1964; Matulović–Suttles, Palma de Mallorca Interzonal 1970; Fuller–Basin, Michigan Open 1992; Boyd–Glimbrant, Alicante 1992; and Pein–de Firmian, Bermuda 1995.


This stunning reversal had a major impact on the match. Staunton had won seven and drawn one of the first eight games, and believed that St. Amant would have resigned the match if he had lost. Instead, St. Amant was able to continue the match for three more weeks, winning another five games, before finally succumbing.


Draw by perpetual check is another often-seen way of swindling a draw from a lost position.


The position at left is from Ivanchuk–Moiseenko, Russian Team Championship, Sochi 2005. Black is down two pawns against the world's sixth highest-rated player. Worse, Ivanchuk's pieces dominate the board. IM Malcolm Pein notes that after almost any sensible move, for example 30.Qc2, Black would be completely lost. White would then threaten 31.Rd6 pinning the knight to the queen, and neither 30...Nf6 31.Bxf6 gxf6 32.Qxh7# nor 30...Nc5 31.Ree7 is an adequate response. 30.Qc2 would also guard against a possible ...Qd1+, the significance of which becomes apparent after seeing the game continuation.


Moiseenko met Ivanchuk's 30.Rb7?? with 30...Nf8!! This not only threatens 31...Nxe6, but also enables Black to meet 31.Rxb8 with 31...Qd1+ 32.Kh2 Qh5+ 33.Kg1 Qd1+, drawing by perpetual check. The perpetual check is based on White's weak back rank combined with his slightly compromised king position (no h-pawn). Note how pieces that are well placed for attacking purposes may be misplaced for defensive purposes. White's rook on e6 was well placed when White had the initiative, but is of no use in stopping the threatened perpetual check. (Similarly, in Rhine–Nagle, Black's rook on g5 was an excellent attacking piece, but was poorly placed to defend Black's back rank or stop White's passed c-pawn.)


White tried 31.Rh6, but could not avoid the perpetual: 31...Rxb7 32.Qxb7 Qd1+ 33.Kh2 Rh5+ 34.Rxh5 34.Kg3!? (hoping for 34...Rxh6?? 35.Qxg7#) is met by 34...Rg5+! and White must repeat moves with 35.Kh2! Rh5+, since 35.Kh3?? Qh1#; 35.Kh4?? Qg4#; and 35.Kf4?? Qg4# all get mated. 34...Qxh5+ 35.Kg3 Qg5+ 36.Kf3 Qf5+ ½–½ since White cannot escape the perpetual check.


David Bronstein, in his immortal losing game, valiantly but unsuccessfully tried to swindle Bogdan Śliwa with a surprise mating attack.


Sometimes a player who is behind in material may achieve a draw by exchanging off, or sacrificing for, all of the opponent's pawns, leaving a position (for example, two knights versus lone king) where the superior side still has a material advantage but cannot force checkmate. (Properly speaking, this may or may not be a "swindle", depending on whether the superior side missed a clear win earlier.) The inferior side is also sometimes able to achieve an ending that is theoretically still lost, but where the win is difficult and may be beyond the opponent's abilities—for example, bishop and knight versus lone king; queen versus rook; two knights versus pawn, which is sometimes a win for the knights; or two bishops versus knight.


White drew similarly in Parr–Farrand, England 1971. From the diagram at above right, play continued 1.Rd5 Bf6 2.Rxf5! On 2...gxf5 3.Kf4, White's king will capture Black's f-pawn, then retreat to h1, reaching a bishop and opposite-colored draw. Instead, Black tried 2...Ke7 3.Rb5 Ke6, "but he soon had to admit that the draw was inevitable."


Schmidt–Schaefer, Rheinhessen 1997 (diagram at above left), is another straightforward example. Black has connected passed pawns, but if White can sacrifice his knights for them he can reach the drawn two knights versus lone king ending. Thus, 50.Nfe4! threatened to capture both pawns with the knights. 50...dxe4 51.Nxe4 Kd5 52.Nxc5! would also achieve that goal. Black tried 50...d4, but agreed to a draw after 51.Nxc5+ Kd6 52.Nb5+! Kxc5 53.Nxd4!


The five examples above arguably are not true swindles, but rather the inferior side's exploitation of a defensive resource available in the position. However, Chandler–Susan Polgar, Biel 1987, (diagram at above right), is a "bona fide" swindle. Polgar has just played 53...Nh6!? (from g8), transparently playing for a rook pawn and wrong-colored bishop draw. GM Chandler obligingly played 54.gxh6+??, expecting 54...Kxh6 55.Kf6! when he will win because Black cannot get her king to h8. Polgar, however, responded 54...Kh8! with the standard draw. White's possession of a second h-pawn is immaterial, and the game concluded 55.Bd5 Kh7 56.Kf7 Kh8! ½–½


The position above left, the conclusion of an endgame study by the American master Frederick Rhine, provides a more complicated example of forcing a draw by material insufficiency. White draws with 5.Nxc4+! Nxc4 If 5...Kc6 6.Nxb6 Kxb6 7.Rxb2+, White's rook draws easily against Black's knight and bishop. 6.Rxb6+ Now Black's best try is 6...Kd5! or 6...Ke7!, when the endgame of rook against two knights and a bishop is a well-established theoretical draw. The more natural 6...Nxb6+ leads to a surprising draw after 7.Kd8! (diagram above), when any bishop move stalemates White, and any other move allows 8.Kxe8, when the two knights cannot force checkmate.


Building a fortress is another method of saving an otherwise lost position. It is often seen in the endgame, for example in endings with bishops of opposite colors (see above).


In Ivanov–Dolmatov, Novosibirsk 1976 (left-most diagram), Black, an down in the endgame, seemingly had a hopeless position. In desperation, he tried 1...e3! White replied 2.Rxb4?? Amatzia Avni wrote, "Amazingly, this greedy collecting of further material gains throws away the win. After 2.fxe3 Black would probably resign." There followed 2...e2 3.Re4 Bxf5 4.gxf5 h4!! (right-most diagram). Despite White's extra rook, the position is drawn: his rook must stay on the e-file to stop Black's pawn from queening, while his king is trapped in the corner. 5.Rg4+ can be met by 5...Kf7 (not 5...Kh6?? 6.Rxh4+) 6.Re4 and now 6...h3, or any king move, holds the draw.


"Zugzwang", though most often used by the superior side, is sometimes available as a swindling technique to the inferior side. Chigorin–Schlechter above is one such instance.


In the position at left, the natural 1...Kb4 would be a fatal blunder, turning a win into a loss after 2.Kd5!, reaching the noted "trébuchet" position (diagram at right), where whoever is on move loses, a situation described as "full-point mutual zugzwang." Instead, 1...Kb3! 2.Kd5 Kb4 wins.


In the movie Tower Heist, Arthur Shaw (played by Alan Alda) mentions "the Marshall Swindle" in a scene where Shaw is playing chess alone, and the main character of Kovaks (played by Ben Stiller) and others are asking where their money is. Shaw specifically mentions the 1912 Master's Tournament of Levitsky versus Marshall and the Swindle in that game, which he describes as "the greatest move in the history of chess". This move is later spoken by Kovaks as Shaw is arrested for fraud at the end of the film.


The exchange in chess refers to a situation in which one player exchanges a (i.e. a bishop or knight) for a rook. The side which wins the rook is said to have "won the exchange", while the other player has "lost the exchange", since the rook is usually more valuable. Alternatively, the side that has won the rook is "up the exchange", and the other player is "down the exchange". The opposing captures often happen on consecutive moves, although this is not strictly necessary. It is generally detrimental to lose the exchange, although occasionally one may find reason to purposely do so; the result is an "exchange sacrifice" (see below). The "minor exchange" is an uncommon term for the exchange of a bishop and knight.


"The exchange" differs from the more general "exchange" or "an exchange", which refers to the loss and subsequent gain of arbitrary pieces, for example to "exchange queens" would mean that each side's queen is .


In the middlegame, the advantage of an exchange is usually enough to win the game if the side with the rook has one or more pawns. In an endgame without pawns, the advantage of the exchange is normally not enough to win (see pawnless chess endgame). The most common exceptions when there are no pawns are (1) a rook versus a bishop in which the defending king is trapped in a corner of the same color as his bishop, (2) a knight separated from its king that may be cornered and lost, and (3) the king and knight are poorly placed .


In the endgame of a rook and a pawn versus a knight and a pawn, if the pawns are passed the rook is much stronger and should win. If the pawns are not passed, the side with knight has good drawing chances if its pieces are well-placed .


In the endgame of a rook and a pawn versus a bishop and pawn, If the pawns are on the same file, the bishop has good chances to draw if the pawns are blocked and the opposing pawn is on a square the bishop can attack; otherwise the rook usually wins. If the pawns are passed the rook normally wins. If the pawns are not passed and are on adjacent files, it is difficult to assess but the bishop may be able to draw .


In an endgame with more pawns on the board (i.e. a rook and pawns versus a minor piece with the same number of pawns) the rook usually wins . This position is typical. The superior side should remember these things:


If the minor piece has an extra pawn (i.e. one pawn for the exchange), the rook should win, but with difficulty. If the minor piece has two extra pawns, the endgame should be a draw .


In this 2004 game between Ivan Sokolov and World Champion Vladimir Kramnik, White gave up the exchange for a pawn in order to create two strong connected passed pawns. The game continued:


and White won on move 41 .


Tigran Petrosian, the World Champion from 1963–1969, was well known for his especially creative use of this device. He once responded (only half jokingly), when asked what was his favourite piece, as saying "The rook, because I can sacrifice it for minor pieces!" In the game Reshevsky versus Petrosian at the 1953 Candidates Tournament in Zurich, he sacrificed the exchange on move 25, only for his opponent to sacrifice it in return on move 30. This game is perhaps the most famous and most frequently taught example of the exchange sacrifice.


There are no open in this position for the rooks to exploit. Black sacrificed the exchange with


With the rook not on e7, the black knight will be able to get to a strong outpost on d5. From there the knight will be attacking the pawn on c3, and if the white bishop on b2 does not move to d2, it will be of little use. In addition, it will be practically impossible to break Black's defense on the white squares. The next few moves were:


The game was drawn on move 41 .


In the tenth game from the 1966 World Chess Championship between defending champion Tigran Petrosian and challenger Boris Spassky contained two exchange sacrifices by White. Black had just moved


White had no choice: 21.Rf2 Rxf4 22.Rxf4 Qg5+, etc. The game continued:


Black is helpless, despite being two exchanges ahead. White won back an exchange on move 29. On move 30 White forced the win of the other rook and the exchange of queens. Black resigned because the position was a winning endgame for White (two knights and five pawns versus one knight and four pawns) . Petrosian won the match by one game to retain his title.


In a 1994 game between World Champion Garry Kasparov and Alexei Shirov, White sacrificed a pure exchange (rook for a bishop) with the move 17. Rxb7!!. As compensation for the sacrifice, Black became weak on the white squares, which were dominated by White's bishop. The exchange sacrifice also deprived Black of the and his remaining bishop was a . During the game, many spectating grandmasters were sceptical whether White's compensation was enough. Black returned the exchange on move 28, making the equal, but White had a strong initiative. Black missed a better 28th move after which White could have forced a draw, but would have had no clear advantage. White won the game on move 38 .


The minor exchange refers to the capture of the opponent's bishop for the player's knight (or, more recently, the stronger for the weaker) . Bobby Fischer used the term , but it is rarely used.


In most chess positions, a bishop is worth slightly more than a knight because of its longer range of movement. As a chess game progresses, pawns tend to get traded, removing support points from the knight and opening up lines for the bishop. This generally leads to the bishop's advantage increasing over time. In general, bishops have relatively higher value in an and knights have relatively higher value in a .


Traditional chess theory espoused by masters such as Wilhelm Steinitz and Siegbert Tarrasch puts more value on the bishop than the knight. In contrast, the hypermodern school favored the knight over the bishop. Modern theory is that it depends on the position, but that there are more positions where the bishop is better than where the knight is better .


Occasions when a knight can be worth more than a bishop are frequent, so this exchange is not necessarily made at every opportunity to do so.


In chess, a backward pawn is a pawn that is behind all pawns of the same color on the adjacent and cannot be safely advanced. In the diagram, the black pawn on the c6-square is backward.


Backward pawns are usually a positional disadvantage because they are unable to be defended by pawns. Also, the opponent can place a piece, usually a knight, on the in front of the pawn without any risk of a pawn driving it away. The backward pawn also prevents its owner's rooks and queen on the same file from attacking the piece placed on the hole.


If the backward pawn is on a half-open file, as in this case, the disadvantage is even greater, as the pawn can be attacked more easily by an opponent's rook or queen on the c-file. Pieces can become weak when they are devoted to protecting a backward pawn, since their obligation to defend the pawn keeps them from being deployed for other uses.


Modern opening theory features several openings in which one of the players deliberately incurs a backward pawn in exchange for some other advantage such as initiative or better . An excellent example is the Sveshnikov Variation of the Sicilian Defence.


After the moves 1. e4 c5 2. Nf3 Nc6 3. d4 cxd4 4. Nxd4 Nf6 (or 4...e5 5.Nb5 d6 – the Kalashnikov Variation) 5. Nc3 e5!? 6. Ndb5 d6 (see diagram), Black has a backward pawn on d6, but White now has to endure a displacement of his knights and an undermining of his after 7. Bg5 a6 8. Na3 b5 9. Bxf6 gxf6 10. Nd5 (dodging the threatened pawn-fork of the knights) 10... f5! (or 10...Bg7 11.c3 [facilitating the knight on a3 to return to the center via Na3–c2–e3] 11...f5!) 11. c3 Bg7, and so on.


In chess, an isolated pawn is a pawn that has no friendly pawn on an adjacent . Isolated pawns are usually a weakness because they cannot be protected by other pawns. The square in front of the pawn may become a good outpost or otherwise a good square for the opponent to anchor pieces. Isolated pawns most often become weaker in the endgame, as there are fewer pieces available to protect the pawn.


Isolated pawns can, however, provide improved development and associated opportunities for that offset or even outweigh their weaknesses. The files adjacent to the isolated pawn are either open or half-open, providing two lanes of attack for the rooks and the queen. The absence of pawns adjacent to the isolated pawn may also mobilize the player's knights and bishops.


An isolated pawn on the d-file is called an isolated queen pawn or simply an isolani. In addition to the open or half-open c- and e-files, the isolated queen pawn can provide a good outpost on the c- and e-file squares diagonally forward of the pawn, which are especially favorable for the player's knights. The isolated queen pawn position favors a attack, freeing both the light and dark-squared bishops due to the absence of friendly pawns on the c- and e-files. Isolated queen pawns suffer, however, from the same weaknesses as other isolated pawns.


Many "textbook" openings lead to isolated pawns, such as the French Defence, Nimzo-Indian Defence, Caro–Kann and Queen's Gambit.


In the endgame, isolated pawns are a weakness in pawn structure because they cannot be defended by other pawns as with connected pawns. In this diagram, the white pawn on the e4-square and the black pawn on a7 are isolated.


Isolated pawns are weak for two reasons. First, the pieces attacking them usually have more flexibility than those defending them. In other words, the attacking pieces enjoy greater freedom to make other threats (win pieces, checkmate, etc.), while the defending pieces are restricted to the defense of the pawn. This is because a piece that is attacking a pawn can give up the attack to do something else, whereas the defending piece must stay rooted to the spot until the attacking piece has moved. The defending piece is thus said to be "tied down" to the pawn.


The second reason is that the square immediately in front of the isolated pawn is weak, since it is immune to attack by a pawn (often providing an excellent outpost for a knight), and the enemy piece located in this square cannot be attacked by rooks because the isolated pawn blocks the file it is on. Thus an isolated pawn provides a typical example of what Wilhelm Steinitz called "weak squares".


An isolated queen pawn (IQP), called an "isolani", is often a special case. An isolated queen pawn is one on the queen's (d-file). The weakness of such a pawn's isolation arises from two factors associated with the absence of both neighboring pawns:


The presence of open or half-open king (e-) and queen's bishop (c-) files, as well as the outposts (for White) at e5 and c5, enable the player with the IQP favourable attacking chances in the middlegame, however. Once the game reaches the endgame, the pawn's isolation becomes more of a weakness than a strength. Therefore, the player with the IQP must take advantage of the temporary strength before an endgame is reached. proposed that with four each, an IQP is an advantage; with three minor pieces each, it is about even; and with two or fewer minor pieces each, it is a disadvantage. Sacrifice of the pawn by White and of the pawn by Black are common themes.


The diagram shows some of the optimum piece placements for both sides in an IQP position.


Making use of this arrangement of pieces White may plan to either advance thematically with d4–d5 opening the position and dissolving the IQP, or use the greater activity of his pieces to launch an attack probably making use of the e5-square for a knight and possibly lifting a rook to the kingside. Typically there may also be a sacrifice on e6 or f7. It is important that White try to use the IQP to support an attack or dissolve it before the endgame as it would then become weak. The advance d4–d5 or a tactic forcing Black to capture a piece on e5 and then recapturing with the d4-pawn would be typical ways of achieving this.


The exchange of a rook for bishop or knight is an "uneven exchange" because a rook is generally more valuable than a bishop or knight. A "minor exchange" is a less commonly used term which refers to the exchange of a bishop for a knight.


A "forced exchange" is an exchange in a position where one of the players is required to initiate or undergo an exchange, either because no alternative play is allowed by chess rules or because the consequence of not making the exchange would be unacceptably detrimental to that player's game. Many exchanges can be offered, but they are not forced. In such cases, the player presented with the possibility of an exchange may decide to make the initial capture, may decline making the initial capture, or may even move to avoid the exchange. The player can weigh the advantages and disadvantages of each move to decide. For a prospective uneven exchange, the values of the pieces are often the deciding factor.


Chess positions are often set up where a player's piece on a certain square is defended by one or more of his other pieces. This typically means that if an opponent's piece captures the defended piece, the capturing piece would be subject to recapture by a defending piece ("defender"). An opponent's piece in a position to capture a given piece could be considered an attacking piece ("attacker"). Positions could develop where a player's piece on a square has one or more attackers and one or more defenders. This is a common way in which exchanges could occur, although there are other ways also.


In such positions, a player with the attacking piece(s) may decide whether it is worthwhile for him to initiate a capture likely to result in recapture, likely decided by the value of the pieces to be taken in the ensuing exchange. Pinned pieces often cannot be counted on being attackers or defenders.


In chess, a sacrifice is the deliberate giving up of a piece by a player, allowing or forcing an opponent to capture the piece or exchange it for a lower value piece.


In a desperado situation, a trapped piece which would inevitably be lost can sometimes be exchanged for another piece, even if it has lower value, in order to minimize net material loss for the player having the inevitably lost piece.


Exchanges of pieces are commonly involved in chess tactics and strategy.


Exchanges are often made to try to improve a position from a strategic point of view. Since positional advantages are often smaller than those due to difference in material value, exchanges to gain a positional advantage are commonly even exchanges in terms of material.


If a player gains material superiority in a game, a strategy can involve making even exchanges to eliminate other pieces for to make the superiority more decisive. The opponent with less material may try to avoid exchanges, but then the player with more material may try to force exchanges anyway.


Strong players commonly play a materially even game with each other, often clearing out their pieces with even exchanges to transition from middlegame to the endgame.


An exchange variation is a type of opening in which there is an early, voluntary exchange of pawns and/or other pieces.


An open file in chess is a with no pawns of either color on it. In the diagram, the e-file is an open file. An open file can provide a line of attack for a rook or queen. Having rooks or queens on open files or half-open files is considered advantageous, as it allows a player to attack more easily, since a rook or queen can move down the file to penetrate the opponent's position.


A common strategic objective for a rook or queen on an open file is to reach its seventh or eighth (the opponent's second or first rank). Controlling the seventh rank is generally worth at least a pawn, as it threatens all the opponent's yet-unmoved pawns to some degree. Controlling the eighth rank is likely to force the opposing king into a more exposed position and puts pressure on any remaining pieces, or if the rank is already clear, allows unobstructed movement behind the enemy forces. Aron Nimzowitsch first recognized the power of a on an open file, writing in his famous book "My System" that the main objective of a rook or queen on an open file is "the eventual occupation of the 7th or 8th rank".


Many games are decided based on this strategy. In the game Anand–Ivanchuk, Amber 2001, Anand sacrificed a pawn to open the d-file. White then used the open file to deploy his rooks to the seventh and eighth ranks and win the game, by exploiting the weakness of Black's a-pawn. White's dominance on the d-file allowed him to maneuver his rooks to aggressive posts deep within Black's defense.


In chess, the fortress is an endgame drawing technique in which the side behind in sets up a zone of protection that the opponent cannot penetrate. This might involve keeping the enemy king out of one's position, or a zone the enemy cannot force one out of (e.g. see the opposite-colored bishops example). An elementary fortress is a theoretically drawn (i.e. a ) position with reduced material in which a passive defense will maintain the draw.


Fortresses pose a problem for computer chess: computers fail to recognize fortress-type positions and are unable to achieve the win against them despite claiming a winning advantage .


Perhaps the most common type of fortress, often seen in endgames with only a few pieces on the board, is where the defending king is able to take refuge in a corner of the board and cannot be chased away or checkmated by the superior side. These two diagrams furnish two classic examples. In both cases, Black simply shuffles his king between a8 and the available square adjacent to a8 (a7, b7, or b8, depending on the position of the white king and pawn). White has no way to dislodge Black's king, and can do no better than a draw by stalemate or some other means.


Note that the bishop and wrong rook pawn ending (i.e. where the pawn is a rook pawn whose promotion square is the color opposite to that of the bishop) in the diagram is a draw even if the pawn is on the seventh rank or further back on the a-. Heading for a bishop and wrong rook pawn ending is a fairly common drawing resource available to the inferior side .


The knight and rook pawn position in the diagram, however, is a draw only if White's pawn is already on the seventh rank, making this drawing resource available to the defender much less frequently. White wins if the pawn is not yet on the seventh rank and is protected by the knight from behind. With the pawn on the seventh rank, Black has a stalemate defense with his king in the corner .


A fortress is often achieved by a sacrifice, such as of a piece for a pawn. In the game between Grigory Serper and Hikaru Nakamura, in the 2004 U.S. Chess Championship, White would lose after 1.Nd1 Kc4 or 1.Nh1 Be5 or 1.Ng4 Bg7. Instead he played


Heading for h1. After another 10 moves the position in the following diagram was reached:


Black has no way of forcing White's king away from the corner, so he played


and after 13.h4 gxh4 the game was drawn by stalemate.


The back-rank defense in some rook and pawn versus rook endgames is another type of fortress in a corner (see diagram). The defender perches his king on the pawn's queening square, and keeps his rook on the back rank (on the "long side" of the king, not, e.g., on h8 in the diagram position) to guard against horizontal checks. If 1.Rg7+ in the diagram position, Black heads into the corner with 1...Kh8! Note that this defense works "only" against rook pawns and knight pawns .


In the ending of a rook versus a bishop, the defender can form a fortress in the "safe" corner—the corner that is not of the color on which the bishop resides (see diagram). White must release the potential stalemate, but he cannot improve his position .


In this position from de la Villa, White draws if his king does not leave the corner. It is also a draw if the bishop is on the other color, so it is not a case of the wrong bishop .


In the diagram, Black draws by moving his rook back and forth between the d6- and f6-squares, or moves his king when checked, staying behind the rook and next to the pawn. This fortress works when all of these conditions are met:


The white king is not able to cross the rank of the black rook and the white queen is unable to do anything useful.


Positions such as these (when the defending rook and king are near the pawn and the opposing king cannot attack from behind) are drawn when (see diagram):


In this position, with Black to move, Black can reach a drawing fortress.


and now 3...Ka3 and several other moves reach the fortress. In the actual game, Black made the weak move 3...Rd3? and lost .


In this 1959 game between Whitaker and Ferriz, White sacrificed a rook for a knight in order to exchange a pair of pawns and reach this position, and announced that it was a draw because (1) the queen cannot mate alone, and (2) the black king and pawn cannot approach to help . However, endgame tablebase analysis shows Black to have a forced win in 19 moves starting with 50... Qc7+ (the only winning move), taking advantage of the fact that the rook is currently unprotected – again illustrating how tablebases are refining traditional endgame theory.


From the diagram, in Salov vs. Korchnoi, Wijk aan Zee 1997, White was able to hold a draw with a rook versus a queen, even with the sides having an equal number of pawns. He kept his rook on the fifth rank blocking in Black's king, and was careful not to lose his rook to a fork or allow a queen sacrifice for the rook in circumstances where that would win for Black. The players agreed to a draw after:


In endings with bishops of opposite colors (i.e. where one player has a bishop that moves on light squares, while the other player's bishop moves on dark squares), it is often possible to establish a fortress, and thus hold a draw, when one player is one, two, or occasionally even three pawns behind. A typical example is seen in the diagram. White, although three pawns behind, has established a drawing fortress, since Black has no way to contest White's stranglehold over the light squares. White simply keeps his bishop on the h3–c8 diagonal .


In an endgame with opposite-colored bishops, positional factors may be more important than material. In this position, Black sacrifices a pawn (leaving him three pawns down) to reach a fortress.


After 4...Be2 5.Kh6 Bd1 6.h5 Black just waits by playing 6...Be2 .


Here are drawing fortresses with two versus a queen . Usually the defending side will not be able to get to one of these positions.


The bishop and knight fortress is another type of fortress in a corner. If necessary, the king can move to one of the squares adjacent to the corner, and the bishop can retreat to the corner. This gives the inferior side enough tempo moves to avoid zugzwang. For example:


In the two bishop versus queen ending, the queen wins if the Lolli position is not reached, but some of them take up to seventy-one moves to either checkmate or win a bishop, so the fifty-move rule comes into play. From the diagram:


and White cannot prevent ... Bb6, which gets back to the Lolli position .


In the two knights fortress, the knights are next to each other and their king should be between them and the attacking king. The defender must play accurately, though .


There are several drawing positions with two knights against a queen. The best way is to have the knights adjacent to each other on a file or rank, with their king between them and the enemy king. This is not a true fortress since it is not static. The position of the knights may have to change depending on the opponent's moves. In this position (Lolli, 1763),


and Black has an ideal defensive position.


If the knights cannot be adjacent to each other on a file or rank, the second best position is if they are next to each other diagonally (see diagram).


The third type of defensive formation is with the knights protecting each other, but this method is more risky .


Sometimes the two minor pieces can achieve a fortress against a queen even where there are pawns on the board. In


Ree-Hort, Wijk aan Zee 1986 (first diagram), Black had the material disadvantage of rook and bishop against a queen. Dvoretsky writes that Black would probably lose after the natural 1...Bf2+? 2.Kxf2 Rxh4 because of 3.Kg3 Rh7 4.Kf3, followed by a king march to c6, or 3.Qg7!? Rxf4+ 4.Kg3 Rg4+ 5.Kf3, threatening 6.Qf6 or 6.Qc7 . Instead, Hort forced a draw with 1... Rxh4!! 2. Kxh4 Bd4! (imprisoning White's queen) 3. Kg3 Ke7 4.Kf3 Ba1 (second diagram), and the players agreed to a draw. White's queen has no moves, all of Black's pawns are protected, and his bishop will shuttle back and forth on the squares a1, b2, c3, and d4.


At the great New York City 1924 tournament, former world champion Emanuel Lasker was in trouble against his namesake Edward Lasker, but surprised everyone by discovering a new endgame fortress . Despite having only a knight for a rook and pawn, White draws by moving his knight back and forth between b2 and a4. Black's only real winning try is to get his king to c2. However, to do so Black has to move his king so far from the pawn that White can play Ka3–b2 and Nc5xb3, when the rook versus knight ending is an easy draw. The game concluded:


If 99...Ke2, 100.Nc5 Kd2 101.Kb2! (101.Nxb3+?? Kc2 and Black wins) and 102.Nxb3 draws.


Bishop versus rook and bishop pawn on the sixth rank.


A bishop can make a fortress versus a rook and a bishop pawn on the sixth rank, if the bishop is on the color of the pawn's seventh rank square and the defending king is in front of the pawn. In this position, White would win if he had gotten the king to the sixth rank ahead of the pawn. Black draws by keeping the bishop on the diagonal from "a2" to "e6", except when giving check. The bishop keeps the white king off "e6" and checks him if he goes to "g6", to drive him away. A possible continuation:


2.f7 is an interesting attempt, but then Black plays 2...Kg7! and then 3...Bxf7, with a draw. 2...Kg7 prevents 3.Kf6, which would win.


The only move to draw, since the bishop must be able to check the king if it goes to g6.


If 7.f7 Bxf7!: the pawn can be safely when the white king is on h6.


Draw, because White cannot make progress .


A "defense perimeter" is a drawing technique in which the side behind in or otherwise at a disadvantage sets up a perimeter, largely or wholly composed of a pawn chain, that the opponent cannot penetrate. Unlike other forms of fortress, a defense perimeter can often be set up in the middlegame with several pieces remaining on the board.


The above example may seem fanciful, but Black achieved a similar defense perimeter in


Here are some other drawing fortresses .


This game between József Pintér and David Bronstein demonstrates the human play of the endgame. The defender has two ideas: (1) keep the king off the edge of the board and (2) keep the knight close to the king. White reaches the semi-fortress after 71. Nb2!, which falls after 75... Kb5!. White gets to a semi-fortress again in another corner after 90. Ng2+. After 100. Ke3 White cannot hold that semi-fortress any longer, but forms one in another corner after 112. Nb7!. On move 117 White claimed a draw by the fifty move rule .


A "positional draw" is a concept most commonly used in endgame studies and describes an impasse other than stalemate. It usually involves the repetition of moves in which neither side can make progress or safely deviate. Typically a advantage is balanced by a positional advantage. Fortresses and perpetual check are examples of positional draws . Sometimes they salvage a draw from a position that seems hopeless because of a material deficit . Grandmaster John Nunn describes a positional draw as a position in which one side has enough material to normally win and he is not under direct attack, but some special feature of the position (often a blockade) prevents him from winning .


A simple example is shown in the game between Lajos Portisch and Lubomir Kavalek. White could have won easily with 1.Be1 Kc6 2.b4. However, play continued 1. b4? Nb8 2. b5 Nc6+! The only way to avoid the threatened 3...Nxa5 is 3.bxc6 Kxc6, but the resultant position is a draw because the bishop is on the wrong color to be able to force the promotion (see above, wrong bishop, and wrong rook pawn) .


Luděk Pachman cites the endgame position in the diagram as a simple example of a positional draw. White on move simply plays waiting moves with the bishop (Bb1–c2–d3). As for Black, "If he is unwilling to allow the transition to the drawn ending of Rook versus Bishop, nothing else remains for him but to move his Rook at [e5] continuously up and down the [e-file]." Pachman explains, "The indecisive result here contradicts the principles concerning the value of the pieces and is caused by the bad position of the black pieces (pinned rook at [e4])." .


This position from a game between Mikhail Botvinnik and Paul Keres in the 1951 USSR Championship is drawn because the black king cannot get free and the rook must stay on the c-. The players agreed to a draw four moves later .


The first diagram shows a position from a game between former World Champion Mikhail Tal and future World Champion Bobby Fischer from the 1962 Candidates Tournament in Curaçao. After 41 moves Tal had the advantage but Fischer sacrificed the exchange (a rook for a knight). The game was drawn on the 58th move .


In this position from a game between Pal Benko and International Master Jay Bonin, White realized that the blockade cannot be broken and the game is a draw despite the extra material .


Can White stop the h-pawn from queening? The position looks lost for White but he does have a defence which seems to defy the rules of logic. White will calmly construct a "fortress" which will hide his pieces from attack. The only weakness in White's "fortress" is the g-pawn. This pawn has to be defended by the bishop and the only square where this can be done safely is from h6.


White threatens to stop the advance of the h-pawn with ...Be5+;


building the fortress immediately does not work: 1.f6? h2 2.Kf8 h1=Q 3.Kg7 (3.Kg8 Qg2 4.Bf8 Qa8 5.Kg7 Kd7 6.Kg8 Ke6 7.Kg7 Kf5 8.Kg8 Bb3 9.Kg7 Qh1−+) 3...Kd7 4.Bb4 Ke6 5.Bd2 Kf5 6.Be3 Qf3 7.Bd2 Qe2 8.Bc1 Qd1 9.Be3 Qd3 10.Bc1 Qc3−+;


2.fxg6? This move destroys the fortress 2...fxg6 3.Be7+ Kc6−+. Chess computer programs have difficulty assessing "fortress" positions because the normal values for the pieces do not apply.


White can draw in another way without the need of a "fortress": 3.fxg6 fxg6 4.Bd8 Kd6 5.Nf6! h2 6.Ne4+ Ke6 7.Nf2 Bd5 8.Bf6 h1=Q 9.Nxh1 Bxh1=;


White has achieved the closing of the long diagonal a8–h1. The only way to avoid this would be for Black to repeat moves. Now White can build his "fortress" without the worry of the queen getting to the back rank via the long diagonal.


5. f6! h2 6. Bf8! h1=Q 7. Bh6!


with the idea of 8.Kf8 and 9.Kg7. White will be safe behind the barrier of pawns. It is a positional draw.


In chess, luft (the German word for "air", sometimes also "space" or "breath") designates the space or square left by a pawn move into which a king (usually a castled one) may then retreat, especially such a space made intentionally to avoid back-rank checkmate. A move leaving such a space is often said to "give the king some luft". The term "luft", "lufting", or "lufted" may also be used (as an English participle) to refer to the movement of the relevant pawn creating luft.


Preventing an opponent from lufting a pawn (for example by pinning it or moving a piece to the square in front of it) is a tactic that may lead to checkmate. A king's access to his luft might also be denied by the opponent subjecting the space or square to attack.


The German "luft" is a close cognate to the English "lift", which is also used in chess, e.g., .


In the diagram, "X"s mark "luft" to which the king can escape back-rank checkmate delivered by the queen. Theoretical enemy knights in the indicated positions deny the king access to his "luft". Black dots indicate areas where threats emanating from enemy pieces capable of capturing diagonally could also deny access. The pawn structure seen in Black's position is , but it is a risk commonly accepted to fianchetto.


Being up a queen, Black will win unless he overlooks the threat of Ng6 (which sets up checkmate via Rh8#). Black wouldn't be able to capture the knight or create luft because his f-pawn is pinned by White's bishop, and his g-pawn cannot advance if a piece is on g6 blockading it. White's king is temporarily safe from check in his luft. (Black can neutralize the threat of Ng6 by playing Qb8, as then Ng6 can be met by the discovered check of Nf5+, winning the checkmate-threatening h4 rook after White reacts.)


An outpost is a square on the fourth, fifth, sixth, or seventh which is protected by a pawn and which cannot be attacked by an opponent's pawn. Such a square is a hole for the opponent . In the figure to the right, c4 is an outpost, occupied by White's knight. It cannot be attacked by Black's pawns – there is no pawn on the d- and Black's pawn on the b-file is too far advanced.


Outposts are a favourable position from which one can launch an attack, particularly using a [[Knight (chess)|knight]]. It is usually a good idea to post knights on opposite color of the opponent's single bishop, other things being equal.


Knights are most efficient when they are close to the enemy's stronghold. This is because of their short reach, something not true of [[Bishop (chess)|bishops]], [[rook (chess)|rooks]] and [[queen (chess)|queens]]. They are also more effective in the centre of the board than on the edges. Therefore, the ideal to be aimed at is an outpost in one of the central (c-, d-, e- or f-) files in an advanced position (e.g. the sixth rank) with a knight. Knowledge of outposts and their effectiveness is crucial in exploiting situations involving an [[Isolated pawn|isolated queen's pawn]].


On the other hand, [[Aron Nimzowitsch|Nimzowitsch]] argued when the outpost is in one of the flank (a-, b-, g- and h-) files the ideal piece to make use of the outpost is a rook. This is because the rook can put pressure on all the squares along the rank.


In chess, connected pawns are two or more pawns of the same color on adjacent , as distinct from isolated pawns. These pawns are instrumental in creating pawn structure because, when diagonally adjacent, like the two rightmost white pawns, they form a , a chain where the one behind protects the one in front. When attacking these chains, the weak spot is the backmost pawn, because it is not protected .


Connected pawns that are both passed, i.e., without any enemy pawns in front of them on the same file or adjacent files, are referred to as connected passed pawns. Such pawns can be very strong in the endgame, especially if supported by other pieces. Often the opponent must sacrifice to prevent one of the pawns from promoting.


Connected passed pawns are usually superior to other passed pawns. An exception is in an opposite-colored bishops endgame with a bishop and two pawns versus a bishop on the opposite color. If the pawns are connected and not beyond their fifth , the position is a theoretical draw whereas widely separated pawns would win.


Two connected pawns on the same without any friendly pawns on adjacent files are called .


There is a saying that two connected passed pawns on the sixth are stronger than a rook. This is true if the other side has nothing but a rook to defend against the pawns (and the defender cannot immediately capture one of the pawns). In this diagram, White wins:


A pawn storm is a chess strategy in which several pawns are moved in rapid succession toward the opponent's defenses.


A pawn storm usually involves adjacent pawns on one side of the board, the (a-, b-, and c-) or the (f-, g-, and h-files).


A pawn storm will often be directed toward the opponent's king after it has castled toward one side (e.g. Fischer–Larsen, 1958). Successive advances of the pawns on that side might rapidly cramp and overwhelm the opponent's position.


A pawn storm might also be directed at queening a passed pawn; the diagram is taken from a game in which Tigran Petrosian was playing the black pieces against Bobby Fischer. Over the next fourteen moves, Petrosian storms his twin pawns down the a- and b- files, forcing Fischer's .


In chess, the pawn structure (sometimes known as the pawn skeleton) is the configuration of pawns on the chessboard. Since pawns are the least mobile of the chess pieces, the pawn structure is relatively static and thus largely determines the strategic nature of the position.


Weaknesses in the pawn structure, such as isolated, doubled, or backward pawns and , once created, are usually permanent. Care must therefore be taken to avoid them (but there are exceptions—for instance see "Boleslavsky hole" below). In the absence of these structural weaknesses, it is not possible to assess a pawn formation as good or bad—much depends on the position of the pieces. The pawn formation does determine the overall strategies of the players to a large extent, however, even if arising from unrelated openings. Pawn formations symmetrical about a vertical line (such as the "e5 Chain" and the "d5 Chain") may appear similar, but they tend to have entirely different characteristics because of the propensity of the kings to castle on the .


Pawn structures often transpose into one another, such as the "Isolani" into the "Hanging pawns", and vice versa. Such transpositions must be considered carefully and often mark shifts in game strategy.


In his 1995 book "Pawn Structure Chess", Andrew Soltis classified the major pawn formations into 17 categories. In 2015, the book "Chess Structures", by Mauricio Flores Rios, further studied the subject, subdividing pawn structures into the 28 most important. For a formation to fall into a particular category, it need not have a pawn position identical to the corresponding diagram, but only close enough that the character of the game and the major themes are unchanged. It is typically the whose position influences the nature of the game the most.


Structures with mutually attacking pawns are said to have "tension". They are ordinarily unstable and tend to transpose into a stable formation with a pawn or exchange. Play often revolves around making the transposition happen under favorable circumstances. For instance, in the Queen's Gambit Declined, Black waits until White the to make the d5xc4 capture, transposing to the Slav formation (see below).


Openings: Primary: Caro–Kann. Other: French, Scandinavian, Trompowsky (colors reversed), Alekhine's.


Themes for White: Outpost on e5, kingside advantage, d4–d5 break, possibility of in the endgame (typically after the exchange of White's d-pawn for Black's c-pawn).


Themes for Black: Weakness of the d4-pawn, ...c6–c5 and ...e6–e5 breaks. The latter break is usually preferable, but harder for Black to achieve.


Openings: Primary: Slav. Other: Catalan, Queen's Gambit Accepted, Queen's Gambit Declined, Nimzo-Indian, Colle System (with colors reversed), London System (with colors reversed), Trompowsky (colors reversed).


Themes for White: Pressure on the c-file, weakness of Black's c-pawn (either after Black's ...b7–b5 or after d4–d5xc6 in response to ...e6–e5), the d4–d5 break.


Themes for Black: e6–e5 and c6–c5 breaks.


Openings: Primary: Sicilian (Najdorf, Richter–Rauzer and Sozin variations), Sicilian Scheveningen, and several other Sicilian variations. Other: King's English (colors reversed).


Themes for White: Pressure on the d-file, space advantage, e4–e5 break (often prepared with f2–f4), f2–f4–f5 push, g2–g4–g5 blitz (see Keres Attack).


Themes for Black: Pressure on the c-file, (and counterplay in general) on the queenside, pressure on White's pawn on e4 or e5, d6–d5 break, e6–e5 transposing into the Boleslavsky hole (see below).


It is often unwise for White to exchange a piece on c6 allowing the recapture bxc6, because the phalanx of Black's center pawns becomes very strong.


Openings: Primary: Sicilian Dragon. Other: (with colors reversed).


Character: Either a razor sharp middlegame with opposite side castling or a moderately sharp game with same side castling. The Sicilian Dragon requires a high level of opening memorization to play properly. This is especially true when it comes to the Yugoslav Attack in which White plays the moves Be3, f3, Qd2 and 0-0-0. Other variations include the following: the Classical Dragon, where White plays Be2 and 0-0; the Tal Attack, defined by Bc4 and 0-0; and the Fianchetto Defense, where White plays g3, Bg2 and 0-0. These less common variations lead to less tactical positions, with a potentially technical endgame.


Themes for White: Outpost on d5, kingside attack (either f2–f4–f5 with kingside castling or h2–h4–h5 with queenside castling), weakness of Black's queenside pawn in the endgame.


Themes for Black: Pressure on the long diagonal, queenside counterplay, exploiting White's often overextended kingside pawns in the endgame.


Opening Lines: The most common variation of the Sicilian Dragon is the Yugoslav Attack. 1. e4 c5 2.Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 g6 6. Be3 (the defining move of the Yugoslav attack) 6... Bg7 7. Qd2 0-0 8. f3 (necessary to prevent Black from playing 8...Ng4 to attack White's dark-squared bishop; 8.f3 also gives e4 extra defense and prepares to launch a pawn storm with the move g4) 8... Nc6 9. 0-0-0 (9.Bc4 is also a very common move in this position) 9... d5 (the main line; other ideas include 9...Nxd4 and 9...Bd7).


Openings: Primary: Sicilian Najdorf, Classical, Sveshnikov, Kalashnikov. Other: Sicilian Prins, Moscow, O'Kelly (2... a6), (with colors reversed).


Themes for White: taking control the d5 , exploiting the backward d6-pawn, f2–f4 break.


Themes for Black: d6–d5 break, queenside minority attack, the c4-square.


It is a paradoxical idea that Black can strive for equality by voluntarily creating a hole on d5. The entire game revolves around control of the d5-square. Black must play very carefully or White will place a knight on d5 and obtain a commanding positional advantage. Black almost always equalizes, and might even obtain a slight edge, if the d6–d5 break can be made. Black has two options for their : on e6 and on b7 (after ...a7–a6 and ...b7–b5). Unusually for an open formation, bishops become inferior to knights because of the overarching importance of d5: White will often exchange Bg5xf6, and Black usually prefers to give up their queen's bishop rather than a knight in exchange for a white knight if it gets to d5.


When White castles queenside, Black often delays castling because their king is quite safe in the .


Openings: Primary: Sicilian, King's Indian Defence. Other: Symmetrical English, King's English (with colors reversed), Queen's Indian Defence, Nimzo-Indian Defence.


Themes for White: Nd4–c2–e3, fianchettoing one or both bishops, the Maróczy hop (Nc3–d5 followed by e4xd5 with terrific pressure on the e-file), kingside attack, c4–c5 and e4–e5 breaks.


Themes for Black: b7–b5 break, f7–f5 break (especially with a fianchettoed king's bishop), d6–d5 break (prepared with ...e7–e6).


The Maróczy bind, named after Géza Maróczy, has a fearsome reputation. Chess masters once believed that allowing the bind was a mistake as Black always gave White a significant advantage. Indeed, if Black does not quickly make a , their will , with minor pieces lacking any squares to move to and possibly becoming cornered or pressed into a weak defense. Conversely, the formation takes time to set up and limits the activity of White's light-squared bishop, which can buy Black some breathing room to accomplish this break.


Openings: Primary: Symmetrical English, Sicilian. Other: King's English (with colors reversed), King's Indian Defence (Sämisch), Queen's Indian Defense, Nimzo-Indian Defence.


The Hedgehog is a formation similar to the Maróczy bind, and shares the strategic ideas with that formation. Typically, the Maróczy bind would transpose into the Hedgehog formation.


Openings: Primary: King's Indian, Old Indian (colors reversed), Ruy Lopez, Italian Game. Other: Ruy Lopez (colors reversed), Italian Game (colors reversed), Sicilian Kramnik. The notation in the rest of this section refers to the colors reversed version.


Themes for White: d6 weakness, c4–c5 push, a3–f8 diagonal, queenside pawn storm.


Themes for Black: d4 weakness, a1–h8 diagonal, f4-square, kingside attack, trading pieces for a superior endgame.


The Rauzer formation is named after Rauzer who introduced it in the Ruy Lopez. It can also rarely occur in the Ruy Lopez with colors reversed.


It is considered to give Black excellent chances because d6 is much less of a hole than White's d4. If the black king's bishop is fianchettoed it is common to see it undeveloped to f8 to control the vital c5- and d6-squares, or remove White's dark-squared bishop, the guardian of the hole.


The Rauzer formation is often misjudged by beginners. In the position on the left, White appears to have a development lead while Black's position appears to be riddled with holes. In reality, it is Black who stands clearly better, because White has no real way to improve their position while Black can improve by exploiting the d4-square (see complete game on Java (Applet) board).


Openings: Primary: King's Indian. Other: English, Pirc, Ruy Lopez, Philidor, Italian Game.


Occurs after exchange of pawns on d4. Name given by Hans Kmoch.


Themes for White: exploitation of d6 weakness, e4–e5 and c4–c5 breaks, minority attack with ...b2–b4–b5.