What is the term? “The simultaneous presentation of information and controls such that the information becomes the affordance through which the user obtains choices and selects actions.” – Roy Fielding
To understand this, we need first to understand what is the benefit: decouple client and server of RESTful API. In current API development, the client follows the API specification and any change at server side will break the client code.
How to solve this? Image if the client follow the action told by the server and the code is adaptive enough to the actions. Then the server can evolve independently.
HATEOAS, an abbreviation for Hypermedia as the Engine of Application State, is a constraint on the REST application architecture.
Check out some examples: