Modules in Python are simply files containing Python code that define functions, variables, and classes, which can be used once they are imported into another Python script.

Modules help break down complex programs into smaller, manageable, and reusable parts. They not only help in maintaining and organizing code efficiently but also in sharing functionalities between projects. Python comes with a rich standard library composed of numerous modules providing ready-to-use functionalities ranging from file I/O operations to network communications.