Most real programs read or write files: a CSV of training data, a JSON config, a log file. This section covers how to do that the modern way — using pathlib for paths and with blocks for safe access.

What’s in this section

1. Reading text files — open, read line by line, read all at once
2. Writing text files — create, overwrite, append
3. Working with CSV — the most common spreadsheet format
4. Working with JSON — the most common API and config format
5. File paths with pathlib — the right way to join, build, and inspect paths

After this section, you can move data in and out of your programs with confidence.