API (Application Programming Interface) helps in communication and data exchange between two software systems. API act as an interface between two applications and allows the two software systems communicate with one another. API is a collection of functions which can be executed by another software program.

API works as; it takes a request from the source, takes that request to the database, fetches the request data from the database and returns a response to the source. API takes the requests from the user and gives the response without exposing the internal details. API acts as Abstraction.

Example: Amazon API, Google Map API