Representational state transfer is a software architectural style that defines a set of constraints to be used for creating Web services. Web services that conform to the REST architectural style, called RESTful Web services, provide interoperability between computer systems on the internet.
What is an API & how to use API in Android (Video)
An API is a set of programming instructions and standards for accessing a web tool or database. A software company releases its API to the public so other software developers can design products that are powered by its service. The API is usually packaged in an SDK.