Modules and Importing: Reusing Code Efficiently
Shows how Python modules let you split code into focused, reusable files. Covers the import statement for loading entire modules, from ... import for pulling in specific functions, and aliases with as to shorten long module names. Demonstrates creating a custom module from scratch and importing it in another file. Surveys useful built-in modules including math, random, os, sys, and datetime. Practical exercise builds a utilities.py module with square, cube, and is_even functions, then imports and calls them from a separate script.