In computer science, a library is a collection of subprograms used to develop software. Libraries contain "helper" code and data, which provide services to independent programs. This allows code and data to be shared and changed in a modular fashion. Some executables are both standalone programs and libraries, but most libraries are not executables. Executables and libraries make references known as links to each other through the process known as linking, which is typically done by a linker.
Most modern operating systems (OS) provide libraries that implement the majority of system services. Such libraries have commoditized the services a modern application expects an OS to provide. As such, most code used by modern applications is provided in these libraries.
