WebDAV is an extension to HTTP/1.1, and it is defined in RFC 4918. It extends the HTTP primitives in order to allow for file manipulation and colaborative authoring.

Some of these primitives include ( from Wikipedia )

COPY copy a resource from one URI to another
LOCK put a lock on a resource. WebDAV supports both shared and exclusive locks.
MKCOL create collections (a.k.a. a directory)
MOVE move a resource from one URI to another
PROPFIND retrieve properties, stored as XML, from a web resource. It is also overloaded to allow one to retrieve the collection structure (also known as directory hierarchy) of a remote system.
PROPPATCH change and delete multiple properties on a resource in a single atomic act
UNLOCK remove a lock from a resource