REST stands for REpresentational State Transfer, and allows you to request an object simply by specifying a URL. In fact browsing the web can be considered a RESTful activity:

1. A client requests a resource at a given URL
2. The server returns the object specified by the URL (a representation)
3. The client parses the resource (a state change)

RESTful webservices are used by specifying the location of a resource and an action to perform. The resource need not be a web page. When web browsing the action is normally get, but a RESTful service may be configured to allow other actions: such as delete, update, post and put. A RESTful webservice such be stateless, that is each state transfer occurs independantly of information regarding previous states. Each request must contain all the necessary information required for the transaction.