Introduction

Python modules are the highest-level components of Python programs. As suggested by their name, modules are modular, capable of being plugged in with other modules as part of an overall program to provide better separation of code while combining together to create a cohesive application.

Modules allow easy reuse of code, and provide separate namespaces to prevent variable shadowing between blocks of code. Variable shadowing involves having duplicate variables in different namespaces, possibly causing the interpreter to use an incorrect variable. Each Python file a developer creates is considered a separate module, allowing different files to be imported into a single, overall file that forms the final application.

Realistically, any Python file can be made a module by simply removing the .py extension; this is most commonly seen when importing libraries. Python packages are collections of modules; what makes a package special is the inclusion of an __init__.py file. We will cover the differences in detail later, so for now just recognize that there are several names for the same items.