12.1. What are Modules?

A module allows you to logically organize your Python code. When code gets to be large enough, the tendency is to break it up into organized pieces which can still interact with each other at a functioning level. These pieces generally have attributes which have some relation to each other, perhaps a single class with its member data variables and methods, or maybe a group of related, yet independently operating functions. These pieces should be shared, so Python allows a module the ability to “bring in” and use attributes from other modules to take advantage of work that has been done, maximizing code reusability. This process of associating attributes from other modules with your module is called importing. Self-contained and organized pieces of Python code that can be shared—in a nutshell, that describes a module.