Modules

A module in Python is a file that contains Python code — for example, functions — that you can reuse in other programs.

Modules are useful in Python because they help to organise code into smaller, easier-to-manage sections. Using modules also makes a program cleaner, more organised and easier to read and understand.

Example 1 - Importing and Using a Custom Module

If you create a file called functions.py containing:

def greet(firstName):
    print(f"Greetings, {firstName}!")

Then in another Python file (main.py) you can use:

import functions

functions.greet("John")

Important

When you create your own modules, both files - the one that defines the functions and the one that imports them - must be saved in the same folder. This allows Python to find the module correctly when you use the import statement.

Show Output

Greetings, John!

Explanation

In the file called functions.py, a function named greet is created. This function takes one parameter called firstName. When the function runs, it displays a message on the screen that says “Greetings,” followed by the name that was given as the parameter.

In the file called main.py, the code imports the functions.py file as a module using the import functions statement. This allows the program to use the greet function that was defined in the other file. The line functions.greet("John") calls the function and passes in the name “John” as the argument.

When the main.py file is run, Python looks inside functions.py to find the greet function and runs it.