API(Application Programming Interface) is a set of instructions, standards or requirements that enables a software or app employ features/services of another app, platform or device for better services. In short, it’s something that let apps communicate with each other.

For example, when we hit on the ‘Connect Facebook’ button on Candy Crush, it does not ask us to enter our Facebook account details. Rather, it accesses the data from the Facebook server and let us enjoy playing – all thanks to API.