In general the Concept of Uniform Resource Identifier (URI) combines the
Identity of an Object. The problem with address is that like in the case for real People the address might change during life time. On the other hand a URI is also a unique Name, therefore it denotes the Identity of a Thing, thus persistent. It is a persistent Identifier for a Web Resource by giving it a Name. This Name does not change during the life cycle. However a Name is as it is in real life not sufficient for finding Things. It need to be known where the Thing is. As it is possible that Things move around, one has to ask somebody for the address. If a Name is given a naming Services can be asked. This retrieves the Uniform Resource Locater which enables to immediate access this Things. Therefore an URI combines both Concepts the Address and the Identity.