What are variable scopes in Python?

In Python, scope determines where a variable is accessible. Python uses the LEGB rule for resolving variable names.

The LEGB Rule:

• L — Local: variables inside the current function.
• E — Enclosing: variables in the outer (enclosing) function.
• G — Global: variables at the module level.
• B — Built-in: Python's built-in names (print, len, range).

x = "global"  # Global

def outer():
    x = "enclosing"  # Enclosing

    def inner():
        x = "local"  # Local
        print(x)  # "local"

    inner()

outer()

The global keyword:

Allows modifying a global variable inside a function:

counter = 0

def increment():
    global counter
    counter += 1

increment()
print(counter)  # 1

The nonlocal keyword:

Allows modifying a variable from an outer (enclosing) function:

def outer():
    count = 0

    def inner():
        nonlocal count
        count += 1
        return count

    return inner

counter = outer()
print(counter())  # 1
print(counter())  # 2