What Is a Module

As programs grow, one file can become too large and hard to manage.

Python uses modules to organize code.

What Is a Module?

A module is a Python file that contains code.

It can contain:

• variables
• functions
• classes

Example:

math_tools.py

This file is a module.

Why Modules Matter

Modules help you:

• split code into files
• reuse code
• keep projects organized
• make code easier to read

Example Without Modules

Everything in one file:

def add(a, b):
    return a + b

print(add(2, 3))

This works, but large projects become messy.

Example Module File

Create a file named:

math_tools.py

Add:

def add(a, b):
    return a + b

Use the Module

Create another file:

main.py

Add:

import math_tools

print(math_tools.add(2, 3))

Output

5

Real Examples of Modules

• math
• random
• os
• json

These are built-in modules.

One Project, Many Modules

Example project:

main.py
users.py
products.py
reports.py

Each file handles one job.

Code Along

Create:

greetings.py

Add function:

def hello():
    print("Hello")

Import it in main.py.

Mini Challenge

Create a module named:

tools.py

Add function:

def double(number):
    return number * 2

Use it in another file.

Expected output:

10

Real World Use Case

Large apps use many modules for users, payments, reports, files, and settings.

Quiz

1. What is a module?
2. What can a module contain?
3. Why are modules useful?
4. Is every .py file a module?

Assignment

Create a module with one function that prints your name, then import it.

Summary

You learned that a module is a Python file used to organize and reuse code.