PEP 8 and naming best practices
PEP 8 (http://www.python.org/dev/peps/pep-0008) provides a style guide for writing Python code. Besides some basic rules such as space indentation, maximum line length, and other details concerning the code layout, PEP 8 also provides a section on naming conventions that most of the codebases follow.
This section provides a quick summary of this PEP, and adds to it a naming best-practice guide for each kind of element. You should still consider reading of PEP 8 document as mandatory.
Why and when to follow PEP 8?
If you are creating a new software package that is intended to be open-sourced, then the answer is simple: always. PEP 8 is de facto the standard code style for most of the open source software in Python. If you want to accept any collaboration from other programmers, then you should definitely stick to PEP 8, even if you have different views on the best code style guidelines. Doing so has the benefit of making it a lot easier for other developers...
