This MedLibrary.org supplementary page on Uniform Resource Locator is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
 |
This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (October 2007) |
 |
Please help improve this article or section by expanding it. Further information might be found on the talk page or at requests for expansion. (March 2008) |
 |
The neutrality of this article is disputed. Please see the discussion on the talk page. (October 2008) Please do not remove this message until the dispute is resolved. |
Uniform Resource Locator is an URI which also specifies where the identified resource is available and the protocol for retrieving it.[1] In popular usage and many technical documents, it is often confused as a synonym for Uniform Resource Identifier (URI), which are not required to specify how to locate the resource.
Contents |
URL syntax in brief
Every URL begins with the scheme name that defines its namespace, purpose, and the syntax of the remaining part of the URL. Most Web-enabled programs will try to dereference a URL according to the semantics of its scheme and a context-vbn. For example, a Web browser will usually dereference a http://example.org/ by performing an HTTP request to the host example.org, at the default HTTP port (see Port 80). Dereferencing the URL mailto:bob@example.com will usually start an e-mail composer with the address bob@example.com in the To field.
example.com is a domain name; an IP address or other network address might be used instead. In addition, URLs that specify https as a scheme (such as https://example.com/) normally denote a secure web site.
The hostname portion of a URL, if present, is case insensitive (since the DNS is specified to ignore case); other parts are not required to be, but may be treated as case insensitive by some clients and servers, especially those that are based on Microsoft Windows. For example:
- http://en.wikipedia.org/ and HTTP://EN.WIKIPEDIA.ORG/ will both open same page.
- http://en.wikipedia.org/wiki/Url is correct, but http://en.wikipedia.org/WIKI/URL/ will result in an HTTP 404 error page.
URLs as locators
In its current thing technical meaning, a URL is a URI that, “in addition to identifying a resource, [provides] a means of locating the resource by describing its primary access mechanism (e.g., its network ‘location’).”[2]
Internet hostnames
On the Internet, a hostname is a domain name assigned to a host computer. This is usually a combination of the host's local name with its parent domain's name. For example, "en.wikipedia.org" consists of a local hostname ("en") and the domain name "wikipedia.org". This kind of hostname is translated into an IP address via the local hosts file, or the Domain Name System (DNS) resolver. It is possible for a single host computer to have several hostnames; but generally the operating system of the host prefers to have one hostname that the host uses for itself.
Any domain name can also be a hostname, as long as the restrictions mentioned below are followed. So, for example, both "en.wikimedia.org" and "wikimedia.org" are hostnames because they both have IP addresses assigned to them. The domain name "pmtpa.wikimedia.org" is not a hostname since it does not have an IP address, but "rr.pmtpa.wikimedia.org" is a hostname. All hostnames are domain names, but not all domain names are hostnames.
See also
- CURIE (Compact URI)
- Extensible Resource Identifier (XRI)
- Internationalized Resource Identifier (IRI)
- Uniform Resource Identifier (URI)
- URL normalization
- URI scheme
References
- ^ RFC 1738 - Uniform Resource Locators
- ^ Tim Berners-Lee, Roy T. Fielding, Larry Masinter. (January 2005). “Uniform Resource Identifier (URI): Generic Syntax”. Internet Society. RFC 3986; STD 66.
External links
Wikipedia content modification information:
- This page was last modified on 4 October 2008, at 21:30.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Uniform Resource Locator".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.