what does an API do
In computer programming, an application programming interface (API) is a set of routines, protocols, and tools for building software applications.An API expresses a software component in terms of its operations, inputs, outputs, and underlying types.n such languages, the API is still distributed as a library. For example, the Java language libraries include a set of APIs that are provided in the form of the JDK used by the developers to build new Java programs.