URL (Uniform Resource Locator)
A Uniform Resource Locator, or URL (pronounces as "earl" (SAMPA: [@rl]) or spelled out), is a standardized address for some resource (such as a document or image) on the Internet. First created by Tim Berners-Lee for use on the World Wide Web, the currently used forms are detailed by IETF standard RFC 2396 (http://www.ietf.org/rfc/rfc2396.txt) (1998).
The URL was a fundamental innovation in creating the World Wide Web. It combines into one simple address the four basic items of information necessary to find a document anywhere on the Internet:
- The protocol to use to communicate with that machine
- The machine or domain name to go to
- An open network port on the target machine connected to some service
- The path or file name on that machine
A typical simple URL can look like:
http://www.wikipedia.org:80/wiki
where
- http: specifies which protocol to use.
- //www.wikipedia.org specifies the domain name to contact.
- :80 specifies the network port number of the remote machine. Under most circumstances, this portion may be omitted entirely. In the case of the http protocol the default value is 80.
- /wiki is the request path on the specified system.
Most Web browsers do not require the user to enter "http://": to go to a Web page one usually just enters the page name (without the slashes) such as www.wikipedia.org/wiki/Train. To go to the homepage one usually just enters the domain name such as www.wikipedia.org
HTTP URLs can also contain additional elements, like a query string (placed after the path and separated from it by a question mark (?)) containing information from a html form with method=get, or a name tag (placed after the path and separated from it by a sharp mark (#)) giving the location within a hypertext page to display. FTP URLs often contain a port number.
Examples:
- http://www.wikipedia.org/w/wiki.phtml?title=Train&action=history
- http://www.wikipedia.org/wiki/Train#Model_railways
This article is licensed under the GNU Free Documentation License, and uses material from the Wikipedia article "url".