Application Programming Interface(A.P.I)

In the simplest terms, APIs are sets of requirements that govern how one application can talk to another. APIs aren’t at all new; whenever you use a desktop or laptop, APIs are what make it possible to move information between programs—for instance, by cutting and pasting a snippet of a LibreOffice document into an Excel spreadsheet. System-level APIs makes it possible for applications like LibreOffice to run on top of an OS like Windows in the first place. These days especially important because they dictate how developers can create new apps that tap into big Web services—social networks like Facebook and google. An API (Application Programming Interface) is best thought of as a contract provided by one piece of computer software to another.