.. _library-intro:

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Introduction

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The "Python library" contains several different kinds of components.

It contains data types that would normally be considered part of the "core" of a

language, such as numbers and lists.  For these types, the Python language core

defines the form of literals and places some constraints on their semantics, but

does not fully define the semantics.  (On the other hand, the language core does

define syntactic properties like the spelling and priorities of operators.)

The library also contains built-in functions and exceptions --- objects that can

be used by all Python code without the need of an :keyword:`import` statement.

Some of these are defined by the core language, but many are not essential for

the core semantics and are only described here.

The bulk of the library, however, consists of a collection of modules. There are

many ways to dissect this collection.  Some modules are written in C and built

in to the Python interpreter; others are written in Python and imported in

source form.  Some modules provide interfaces that are highly specific to

Python, like printing a stack trace; some provide interfaces that are specific

to particular operating systems, such as access to specific hardware; others

provide interfaces that are specific to a particular application domain, like

the World Wide Web. Some modules are available in all versions and ports of

Python; others are only available when the underlying system supports or

requires them; yet others are available only when a particular configuration

option was chosen at the time when Python was compiled and installed.

This manual is organized "from the inside out:" it first describes the built-in

data types, then the built-in functions and exceptions, and finally the modules,

grouped in chapters of related modules.  The ordering of the chapters as well as

the ordering of the modules within each chapter is roughly from most relevant to

least important.

This means that if you start reading this manual from the start, and skip to the

next chapter when you get bored, you will get a reasonable overview of the

available modules and application areas that are supported by the Python

library.  Of course, you don't *have* to read it like a novel --- you can also

browse the table of contents (in front of the manual), or look for a specific

function, module or term in the index (in the back).  And finally, if you enjoy

learning about random subjects, you choose a random page number (see module

:mod:`random`) and read a section or two.  Regardless of the order in which you

read the sections of this manual, it helps to start with chapter :ref:`builtin`,

as the remainder of the manual assumes familiarity with this material.

Let the show begin!