Hypermedia as the Engine of Application State(HATEOAS)

Wikipedia says HATEOAS, an abbreviation for Hypermedia as the Engine of Application State, is a constraint of the REST application architecture that distinguishes it from most other network application architectures.
The principle is that a client interacts with a network application entirely through hypermedia provided dynamically by application servers.
A REST client needs no prior knowledge about how to interact with any particular application or server beyond a generic understanding of hypermedia.
Contrast this with e.g. a service-oriented architecture (SOA), where clients and servers interact through a fixed interface shared through documentation or an interface description language (IDL).
The HATEOAS constraint serves to decouple client and server in a way that allows the server to evolve functionality independently.
Below article gives more information regarding this.
http://blog.zenika.com/index.php?post/2012/06/13/HATEOAS-with-Spring-MVC-REST