HTTP/1.1 has a simple data model: Ultimately, all Web objects are resources, which can be addressed by Uniform Resource Identifiers (URIs). WebDAV extends this data model while still keeping it rather simple.
A collection is a special kind of resource that contains other resources. As a type of resource, a collection is addressable.
All resources have properties with names and values, but properties are not independently addressable and do not have URIs.
Any resource may be locked. Locks are not independently addressable either.
A data model allows clients to have assumptions about the way information will be organized on the server and to use these assumptions to access information on behalf of the user. A consistent data model ...