Naming

Underscores

One at the Start

Using one underscore at the start of a name will make that object protected.

Example: _var

Two at the Start

Using two underscores at the start of the name will make that object class-private.

Example: __var

Two at the Start and Two at the End

Two at the start and the end is usually saved for built-in classes and has no real use outside of them.

Example: __var__

There are build-in variables and methods following this pattern, such as __init__.

Variables

Variables in Python are typically all lowercase, with words separated by underscores. This is commonly called "Snake Case". Variables can not begin with numbers, but can include numbers after the fact. A typical name would be as follows: my_var.

Constants

Python doesn't really have constants, though one still can created them their own way. Names of constants are usually in all uppercase, such as: MY_CONST.

Functions/Methods

Functions and methods follow the naming scheme of variables, in fact, they're the same.

Classes

Classes follow upper Camel Case, meaning that each word starts with a capital letter, and there are no separations of words, not even underscores. An example of this is: MyClass.