Clients should express their preferred state through a host of request messages. A resource's current state gets communicated by the server to any client through a response message. For example, a wiki page editor can send a message to the server requesting to transfer a representation. The representation change may suggest a page update, which is the new state for the server-hosted and -managed web page. However, the server takes the call to accept or deny the client's request. As indicated in the previous paragraph, the self-descriptive messages may include metadata to carry and convey the additional details regarding the resource state, the representation format and size, and the message itself:
The core operations ...
