API: API stands for Application Program Interface. API is a series of protocols, tools and routines used to build software applications. A majority of search products have API programs.

The API defines how software components interact with each other. It's also used in the programming of graphical user interface (GUI) components. The better an API is, the easier it is to develop a program; all the building blocks are provided and a programmer just has to put them together.

APIs can be used for operating systems, websites or applications, and because of the wide array of possible uses, there are several different types of APIs. An API is used in Windows, for instance, when you copy text from one application and paste it into another.

Most operating systems like Windows or IoS provide an API to programmers so that they can write and deploy applications that will be compatible with the system. Many websites specify APIs as well.

Web APIs may be used by third-party software developers to create custom software for end users.

Selling sites like Amazon and Ebay also provide APIs so that retailers that exist outside of their site can create specialized web stores within the site's infrastructure.