View source for Application programming interface

In [[computer programming]], an '''application programming interface''' ('''API''') is a set of routines, protocols, and tools for building [[Software application|software applications]]. 

An API expresses a software component in terms of its operations, inputs, outputs, and underlying types. 

An API defines functionalities that are independent of their respective implementations, which allows definitions and implementations to vary without compromising each other. 

A good API makes it easier to develop a program by providing all the building blocks. A programmer then puts the blocks together.

== APIs and Programming GUI Components ==

In addition to accessing databases or computer hardware, such as hard disk drives or video cards, an API can ease the work of programming GUI components. 

For example, an API can facilitate integration of new features into existing applications (a so-called "plug-in API"). An API can also assist otherwise distinct applications with sharing data, which can help to integrate and enhance the functionalities of the applications.

== API libraries ==

APIs often come in the form of a library that includes specifications for routines, data structures, object classes, and variables. 

In other cases, notably [[SOAP]] and [[REST]] services, an API is simply a specification of remote calls exposed to the API consumers.

== External links ==

* [https://en.wikipedia.org/wiki/Application_programming_interface Appplication programming interface] @ Wikepedia