Library (computing)

In computing, a library is a collection of resources that can be used during software development to implement a computer program. Commonly, a library consists of executable code such as compiledfunctions and classes, or a library can be a collection of source code. A resource library may contain data such as images and text.

A library can be used by multiple, independent consumers (programs and other libraries). This differs from resources defined in a program which can usually only be used by that program. When a consumer uses a library resource, it gains the value of the library without having to implement it itself. Libraries encourage software reuse in a modular fashion. Libraries can use other libraries resulting in a hierarchy of libraries in a program.

When writing code that uses a library, a programmer only needs to know how to use that library's application programming interface (API) without understanding its internal mechanics. For example, a program could use a library that abstracts a complicated system call so that the programmer can use the system feature without spending time to learn the intricacies of the system function.