course/pr_1114/en/chapter5/1.md

# Introduction[[introduction]]

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In [Chapter 3](/course/chapter3) you got your first taste of the 🤗 Datasets library and saw that there were three main steps when it came to fine-tuning a model:

1. Load a dataset from the Hugging Face Hub.
2. Preprocess the data with `Dataset.map()`.
3. Load and compute metrics.

But this is just scratching the surface of what 🤗 Datasets can do! In this chapter, we will take a deep dive into the library. Along the way, we'll find answers to the following questions:

* What do you do when your dataset is not on the Hub?
* How can you slice and dice a dataset? (And what if you _really_ need to use Pandas?)
* What do you do when your dataset is huge and will melt your laptop's RAM?
* What the heck are "memory mapping" and Apache Arrow?
* How can you create your own dataset and push it to the Hub?

The techniques you learn here will prepare you for the advanced tokenization and fine-tuning tasks in [Chapter 6](/course/chapter6) and [Chapter 7](/course/chapter7) -- so grab a coffee and let's get started!

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