Overview of REST web service concepts (Representational State Transfer).
REST is a radically different approach for web services compared to the combo SOAP/WSDL.
REST defines an architectural style for web applications and web services.
REST makes heavy use of the underlying HTTP protocol.
REST itself is not a protocol but defines architectural principles based on the concept of addressable resources and a uniform access to these resources based on the well-known HTTP-methods GET, POST, PUT and DELETE.
The state of a client (web service consumer) is controlled by the REST web service through connected links between resources (resource oriented architecture). The client state however is stored on the client itself thus greatly increasing scalability of REST-based architectures.
The REST paradigm has mostly superseded SOAP / WSDL type web services in many enterprise applications. This is largely owed to the fact that the underlying HTTP protocol is well understood and proved its scalability in the WWW.