Documents may contain hyperlinks to each other. The name of the machine hosting the resource. The name of the resource itself, given as a path. The second is normally the address of the machine where the data or service is situated. Additional portions may define the names of files, the port to link to, or the document to search for in a database.
Most Web browsers permit the user to enter a URL to link to that document or service.
Hyperlinks can be made not only to other media, but also to other network services. Web browsers are not simply Web clients, but are also full-featured FTP, Gopher, and telnet clients. Some URLs refer to a location within a resource. A relative URL doesn't contain any naming scheme information. Its path generally refers to a resource on the same machine as the current document.