# 1.1 Include Files

All function, type and macro definitions needed to use the Python/C API are included in your code by the following line:

`#include "Python.h"`

This implies inclusion of the following standard header files: stdio.h, string.h, errno.h, and stdlib.h (if available).

All user visible names defined by Python.h (except those defined by the included standard headers) have one of the prefixes `Py` or `_Py`. Names beginning with `_Py` are for internal use only. Structure member names do not have a reserved prefix.

Important: user code should never define names that begin with `Py` or `_Py`. This confuses the reader, and jeopardizes the portability of the user code to future Python versions, which may define additional names beginning with one of these prefixes.