API (Application Programming Interface)

A set of functions that gives programmers access to another application's internal features from within their own application.

An Application Programming Interface (API) is a set of classes that you can use in your own application. Sometimes called libraries or modules, APIs enable you to write an application without reinventing common pieces of code. For example, a networking API is something your application can use to make network connections, without your ever having to understand the underlying code.

Formatting instructions or tools used by an application developer to link and build hardware or software applications.