Modules & pip

Import code

A module is a file of ready-made code you can reuse. Python ships with a huge standard library of them. You bring a module into your program with import, then use its tools through the dot.

import math
print(math.sqrt(16))    # 4.0

from datetime import date
print(date.today())

The first import math loads the whole maths module, so math.sqrt(16) asks it for the square root of 16, which is 4.0. The second style, from datetime import date, pulls just one tool (date) out of the datetime module so you can use it by name — date.today() then returns today’s date. Use import x when you want the whole module, and from x import y when you only need one piece.

Install packages with pip

Beyond the built-in modules, the world has written millions more. Python’s package manager pip installs these free libraries (like Django!) from an online store called PyPI.

pip install requests
# then in code:
# import requests

You run pip install requests in the terminal, not inside your Python file. It downloads the requests package and saves it on your computer. After that, any of your programs can pull it in with import requests — exactly like the built-in modules above.