Introduction¶

The “Python library” contains several different kinds of components.

It contains data types that would normally be considered part of the “core” of alanguage, such as numbers and lists. For these types, the Python language coredefines the form of literals and places some constraints on their semantics, butdoes not fully define the semantics. (On the other hand, the language core doesdefine syntactic properties like the spelling and priorities of operators.)

The library also contains built-in functions and exceptions — objects that canbe used by all Python code without the need of animport statement.Some of these are defined by the core language, but many are not essential forthe core semantics and are only described here.

The bulk of the library, however, consists of a collection of modules. There aremany ways to dissect this collection. Some modules are written in C and builtin to the Python interpreter; others are written in Python and imported insource form. Some modules provide interfaces that are highly specific toPython, like printing a stack trace; some provide interfaces that are specificto particular operating systems, such as access to specific hardware; othersprovide interfaces that are specific to a particular application domain, likethe World Wide Web. Some modules are available in all versions and ports ofPython; others are only available when the underlying system supports orrequires them; yet others are available only when a particular configurationoption was chosen at the time when Python was compiled and installed.

This manual is organized “from the inside out:” it first describes the built-infunctions, data types and exceptions, and finally the modules, grouped inchapters of related modules.

This means that if you start reading this manual from the start, and skip to thenext chapter when you get bored, you will get a reasonable overview of theavailable modules and application areas that are supported by the Pythonlibrary. Of course, you don’thave to read it like a novel — you can alsobrowse the table of contents (in front of the manual), or look for a specificfunction, module or term in the index (in the back). And finally, if you enjoylearning about random subjects, you choose a random page number (see modulerandom) and read a section or two. Regardless of the order in which youread the sections of this manual, it helps to start with chapterBuilt-in Functions, as the remainder of the manual assumes familiarity withthis material.

Let the show begin!