"alability.is not just about handling more traffic — it's about maintaining consistent performance as complexity grows. horizontal scaling introduces challenges around data consistency and coordination between nodes. ",
"data.consistency in distributed systems is a hard problem. cap theorem reminds us that we cannot have simultaneously perfect consistency and availability in the presence of network partitions. ",
"ng.is an often overlooked but essential part of the development cycle. unit tests verify individual components in isolation. integration tests ensure components work together. end-to-end tests validate the entire system. "
