PyWin32 is a Python wrapper to Windows specific functionality and C APIs.
Want to work with the registry in Windows? Or maybe the clipboard, windows credentials, file attributes, etc? PyWin32 wraps the C functions, so you don't have to write C code to do this.
This page lists a ton of C functions that are wrapped by PyWin32 (e.g. CreateWindowEx).
Here is a very useful page on Stack Overflow that led me to this information, and details where to find the documentation.