Underscore Naming

Single Leading Underscore:

• _var

• Indicating a name is protected, for internal use. Not enforced by python interpreter

Double Leading Underscore:

• __var
• Indicating a name is private. Enforced by interpreter, attempt to call it will trigger AttributeError

Double Leading Trailing Underscore:

• __var__
• Special methods (magic methods) defined by python language, avoid naming your own attribute

Single Trailing Underscore:

• var_
• Avoid naming conflict with python keywords

Single Underscore:

• _
• Temporary variable name, variables that are never used
• Example:

a, b, c, d = ([] for _ in range(4))

for _ in random_list:
    some_operation()

Reference

Dan Bader - The Meaning of Underscores in Python

Tutorials Teacher - Python - Public, Protected, Private Members