This can be useful when you need to wrap a C library, which is often needed with older libraries and interfaces to older hardware.

Simple Example:
http://fsckd.com/2009/4/25/simple-python-ctypes-example

Simple Example using Visual Studio:
http://www.lejordet.com/2009/04/simple-python-ctypes-example-in-windows/


This tutorial is very easy to read:
http://donaldkenney.110mb.com/CTYPES.HTM

This is a nice complete tutorial:
http://python.net/crew/theller/ctypes/tutorial.html

ctypes provide a native way for python to make calls to C libraries.