Python libraries are collections of pre-written code that help developers perform common tasks more efficiently. They provide functions and methods that can be reused, saving time and effort in programming. Popular libraries include NumPy for numerical computations, Pandas for data manipulation, and Matplotlib for data visualization. These libraries are easily installed and integrated into Python projects, allowing users to leverage existing solutions rather than writing code from scratch. This modular approach enhances productivity and encourages collaboration within the Python community, as developers can share and improve upon each other's work.