Python takes a “batteries included” approach to the standard library. Many other languages ship with a small number of common packages and require you to look elsewhere for important functionality. Although Python also has an impressive repository of communitybuilt modules, it strives to provide, in its default installation, the most important modules for common uses of the language.
The full set of standard modules is too large to cover in this book. But some of these builtin packages are so closely intertwined with idiomatic Python that they may as well be part of the language specification. These essential built-in modules are especially important when writing the intricate, error-prone parts of programs.