The Browser (Netscape, Mosaic, Explorer)

URL - Uniform Resource Locator - is a unique descriptor that can identify any document (plain or hypertext), graphic, Usenet article, computer, or even an archive of files anywhere on the Internet or your machine.

The format for specifying a URL is consistent throughout the many services that URL encompasses, including Usenet news, Web HTML documents, and FTP archives. As a general rule, a URL is composed of the following elements: 

service  ://  hostname :port / directory-path

Some examples: 

     http://www.intuitive.com/
     ftp://gatekeeper.dec.com/hypertext
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