What is Web/REST API?

A Web/REST API (Representational State Transfer Application Programming Interface) is an architectural style for designing networked applications. It relies on a stateless, client-server, cacheable communications protocol -- typically HTTP. REST APIs define a set of functions which developers can perform requests and receive responses, like getting data, creating data, updating data or deleting data. They are commonly used for building web services and mobile applications because of their simplicity, scalability, and flexibility.