1.. _library-intro: 2 3************ 4Introduction 5************ 6 7The "Python library" contains several different kinds of components. 8 9It contains data types that would normally be considered part of the "core" of a 10language, such as numbers and lists. For these types, the Python language core 11defines the form of literals and places some constraints on their semantics, but 12does not fully define the semantics. (On the other hand, the language core does 13define syntactic properties like the spelling and priorities of operators.) 14 15The library also contains built-in functions and exceptions --- objects that can 16be used by all Python code without the need of an :keyword:`import` statement. 17Some of these are defined by the core language, but many are not essential for 18the core semantics and are only described here. 19 20The bulk of the library, however, consists of a collection of modules. There are 21many ways to dissect this collection. Some modules are written in C and built 22in to the Python interpreter; others are written in Python and imported in 23source form. Some modules provide interfaces that are highly specific to 24Python, like printing a stack trace; some provide interfaces that are specific 25to particular operating systems, such as access to specific hardware; others 26provide interfaces that are specific to a particular application domain, like 27the World Wide Web. Some modules are available in all versions and ports of 28Python; others are only available when the underlying system supports or 29requires them; yet others are available only when a particular configuration 30option was chosen at the time when Python was compiled and installed. 31 32This manual is organized "from the inside out:" it first describes the built-in 33functions, data types and exceptions, and finally the modules, grouped in 34chapters of related modules. 35 36This means that if you start reading this manual from the start, and skip to the 37next chapter when you get bored, you will get a reasonable overview of the 38available modules and application areas that are supported by the Python 39library. Of course, you don't *have* to read it like a novel --- you can also 40browse the table of contents (in front of the manual), or look for a specific 41function, module or term in the index (in the back). And finally, if you enjoy 42learning about random subjects, you choose a random page number (see module 43:mod:`random`) and read a section or two. Regardless of the order in which you 44read the sections of this manual, it helps to start with chapter 45:ref:`built-in-funcs`, as the remainder of the manual assumes familiarity with 46this material. 47 48Let the show begin! 49 50 51.. _availability: 52 53Notes on availability 54===================== 55 56* An "Availability: Unix" note means that this function is commonly found on 57 Unix systems. It does not make any claims about its existence on a specific 58 operating system. 59 60* If not separately noted, all functions that claim "Availability: Unix" are 61 supported on macOS, which builds on a Unix core. 62 63