Software library

A software library is a pre-compiled collection of reusable code (functions, classes, routines) that developers link to their programs to execute specific, complex tasks.

A software library acts as a digital toolbox: it provides rigorously tested, pre-written code modules for common development needs. This collection of resources (e.g., executable code or configuration data) is accessed via a defined Application Programming Interface (API), eliminating the need to write redundant code from scratch. Utilizing libraries like Python's NumPy (for numerical computing) or the JavaScript library React (for user interfaces) accelerates development cycles, reduces errors, and ensures code standardization across projects. The core benefit is efficiency: developers focus on unique application logic, leveraging the library for established, low-level functionality.

https://en.wikipedia.org/wiki/Library_(computing)