Source: 📖 Effective Python item 2

Pythonic naming conventions

PEP 8 style guide suggests the following guidelines for naming different elements in your code:

• Functions, variables and attributes: lowercase_underscore
• Protected instances: _leading_underscore
• Private instance attributes: __leading_dunder
• Classes (including Exceptions): CapitalisedWord
• Module-level constants: ALL_CAPS
• Instance methods in classes use self to refer to the object as the first parameter
• Class methods use cls to refer to the class as the first parameter