URIs and URI references are organized with a top-level naming structure which follows a scheme or design name.
A URI is defined by one of many standard schemes. Refer to IETF RFC 2396 for details about semantics and syntax.
<scheme>:<usersinformation>@<thehost>:<port><path>;<parameters>
URI schemes or protocols often have the exact same name, and they can be used for a variety of purposes. Most commonly, the Hypertext Transfer Protocol (http) scheme is used for Web interaction. URIs are also used for XML namespaces and RDF resource identifiers, which are unrelated to the protocols. Finally, there are instances in which the scheme is not connected to a protocol at all (for example, a simple directory path such as file).