Module

A file of Python code you can import and reuse in other programs.

A module is simply a .py file whose functions, classes, and variables you can reuse elsewhere with import. Python ships with a large standard library of ready-made modules — for math, dates, random numbers, files, and much more. After importing, reach inside with a dot (math.sqrt) or pull specific names out with from math import sqrt.

Example 
import math               # a standard-library module
print(math.sqrt(16))      # use one of its functions
print(math.pi)            # and one of its constants

from datetime import date
print(date(2025, 1, 1).year)
Output 
4.0
3.141592653589793
2025

Where this shows up in real Python

Modules let you reuse code across files and tap the standard library — os, json, datetime, and many more.

Commonly used Module tools

  • import json — bring in a whole module
  • from pathlib import Path — import just one name
  • import numpy as np — import under a shorter alias
  • dir(module) — list what a module offers
  • help(thing) — read its built-in documentation

Official documentation: Python Tutorial: Modules

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