Scope

Variables do not always work everywhere in a program.

Some variables only work inside a function.

Some variables can be used in many places.

This idea is called scope.

What Is Scope?

Scope means where a variable can be used.

Think of scope as the area where a variable is visible and available.

Two Main Types of Scope

• Local scope
• Global scope

Local Scope

A local variable is created inside a function.

It can only be used inside that function.

def greet():
    name = "Sara"
    print(name)

greet()

Output

Sara

The variable name works inside the function.

Outside the Function

def greet():
    name = "Sara"

greet()
print(name)

This gives an error because name only exists inside the function.

Global Scope

A global variable is created outside a function.

It can be used in many places.

city = "Toronto"

def show_city():
    print(city)

show_city()
print(city)

Output

Toronto
Toronto

The variable city is outside the function, so it is global.

Local and Global Together

If a local variable has the same name, Python uses the local one inside the function.

name = "John"

def show_name():
    name = "Maya"
    print(name)

show_name()
print(name)

Output

Maya
John

Why Scope Matters

Scope helps avoid confusion.

It keeps variables organized and prevents accidental changes.

Code Along

country = "Canada"

def show_country():
    print(country)

show_country()

Output

Canada

Mini Challenge

Build a scope checker.

Steps:

• Create a global variable called color with value Blue
• Create a function that prints color
• Call the function
• Print color again outside the function

Expected output:

Blue
Blue

Real World Use Case

Programs use scope to manage data in functions, apps, games, and large systems with many variables.

Quiz

1. What does scope mean?
2. Where does a local variable work?
3. Where is a global variable created?
4. Which variable is used first inside a function if names match?

Assignment

Create a global variable called language. Print it inside a function and outside the function.

Summary

You learned that scope controls where variables can be used, and the difference between local and global variables.