View source for URL

{{short description|Web address to a particular file or page}}
{{pp-semi-indef}}
{{other uses}}
{{Use dmy dates|date=May 2020|cs1-dates=y}}
{{Infobox technology standard
| title             = URL
| long_name         = Uniform resource locator  
| native_name       = 
| native_name_lang  = 
| image             = 
| caption           = 
| status            = Published
| year_started      = 
| version           = [https://url.spec.whatwg.org Living Standard] 
| version_date      = 2023 
| preview           = 
| preview_date      = 
| organization      = [[Internet Engineering Task Force]] (IETF)
| committee         = [[Web Hypertext Application Technology Working Group]] (WHATWG)
| base_standards    = {{Plainlist|
* {{IETF RFC|1738}}. – Uniform Resource Locators (URL).
* {{IETF RFC|3986}}. – Uniform Resource Identifier (URI): Generic Syntax.
* {{IETF RFC|4248}}. – The telnet URI Scheme.
* {{IETF RFC|4266}}. – The gopher URI Scheme.
* {{IETF RFC|6068}}. – The 'mailto' URI Scheme.
* {{IETF RFC|6196}}. – Moving mailserver: URI Scheme to Historic.
* {{IETF RFC|6270}}. – The 'tn3270' URI Scheme.
}}
| related_standards =[[Uniform Resource Identifier|URI]], [[Uniform Resource Name|URN]] 
| abbreviation      = URL
| domain            = [[World Wide Web]]
| license           = [https://creativecommons.org/licenses/by/4.0/ CC BY 4.0]
| website           = {{URL|https://url.spec.whatwg.org}}
|first_published = {{Start date and age|1994}}|authors=[[Tim Berners-Lee]]|series=Request for Comments (RFC)|editors=[[Anne van Kesteren]]}}
A '''uniform resource locator''' ('''URL'''), colloquially known as an '''address''' on the [[World Wide Web|Web]],{{sfnp|W3C|2009}} is a reference to a [[web resource|resource]] that specifies its location on a [[computer network]] and a mechanism for retrieving it. A URL is a specific type of [[Uniform Resource Identifier]] (URI),<ref>{{Cite web |url=https://zzz.buzz/2017/09/19/forward-and-backslashes-in-urls/ |title=Forward and Backslashes in URLs |website=zzz.buzz |access-date=19 September 2018 |archive-date=2018-09-04  |archive-url=https://web.archive.org/web/20180904050005/https://zzz.buzz/2017/09/19/forward-and-backslashes-in-urls/ |url-status=live }}</ref>{{sfnp|RFC 3986|2005}} although many people use the two terms interchangeably.{{sfnp|Joint W3C/IETF URI Planning Interest Group|2002}}{{efn|A URL implies the means to access an indicated resource and is denoted by a protocol or an access mechanism, which is not true of every URI.{{sfnp|RFC 2396|1998}}{{sfnp|Joint W3C/IETF URI Planning Interest Group|2002}} Thus <code><nowiki>http:</nowiki>//www.example.com</code> is a URL, while <code>www.example.com</code> is not.<ref>{{Cite web |url=https://danielmiessler.com/study/url-uri/#gs.Hs64zOs |title=The Difference Between URLs and URIs |author-last=Miessler |author-first=Daniel |access-date=2017-03-16  |archive-date=2017-03-17  |archive-url=https://web.archive.org/web/20170317054341/https://danielmiessler.com/study/url-uri/#gs.Hs64zOs |url-status=live }}</ref>}} URLs occur most commonly to reference [[web page]]s ([[Hypertext Transfer Protocol|HTTP]]/[[HTTPS]]) but are also used for file transfer ([[File Transfer Protocol|FTP]]), email ([[mailto]]), database access ([[Java Database Connectivity|JDBC]]), and many other applications.

Most [[web browser]]s display the URL of a web page above the page in an [[address bar]]. A typical URL could have the form <code><nowiki>http:</nowiki>//www.example.com/index.html</code>, which indicates a protocol (<code>http</code>), a [[hostname]] (<code>www.example.com</code>), and a file name (<code>index.html</code>).

==History==
Uniform Resource Locators were defined in {{IETF RFC|1738}} in 1994 by [[Tim Berners-Lee]], the inventor of the [[World Wide Web]], and the URI working group of the [[Internet Engineering Task Force]] (IETF),{{sfnp|W3C|1994}} as an outcome of collaboration started at the IETF Living Documents [[Birds of a feather (computing)|birds of a feather]] session in 1992.{{sfnp|W3C|1994}}{{sfnp|IETF|1992}}

The format combines the pre-existing system of [[domain name]]s (created in 1985) with [[Path (computing)|file path]] syntax, where [[Slash (punctuation)|slashes]] are used to separate [[Folder (computing)|directory]] and [[filename]]s. Conventions already existed where server names could be prefixed to complete file paths, preceded by a double slash (<code>//</code>).{{sfnp|Berners-Lee|2015}}

Berners-Lee later expressed regret at the use of dots to separate the parts of the [[domain name]] within [[URI]]s, wishing he had used slashes throughout,{{sfnp|Berners-Lee|2015}} and also said that, given the colon following the first component of a URI, the two slashes before the domain name were unnecessary.{{sfnp|BBC News|2009}}

Early [[WorldWideWeb]] collaborators including Berners-Lee originally proposed the use of UDIs: Universal Document Identifiers.<!-- cite: Tim Berners-Lee, Jean-François Groff, Robert Cailliau. "Universal Document Identifiers on the Network". CERN. <file://info.cern.ch./pub/www/doc/udi1.ps> -->
An early (1993) draft of the HTML Specification<ref>{{cite tech report |title=Hypertext Markup Language (draft RFCxxx) |author-first1=Tim |author-last1=Berners-Lee |author-link1=Tim Berners-Lee |author-first2=Daniel "Dan" |author-last2=Connolly |author-link2=Daniel Connolly |date=March 1993 |page=28 |url=https://www.ucc.ie/archive/curia/dtds/html-spec.ps |access-date=2017-10-23  |archive-date=2017-10-23  |archive-url=https://web.archive.org/web/20171023232709/https://www.ucc.ie/archive/curia/dtds/html-spec.ps |url-status=live }}</ref> referred to "Universal" Resource Locators. This was dropped some time between June 1994 ({{IETF RFC|1630|link=no}}) and October 1994 (draft-ietf-uri-url-08.txt).<ref>{{cite tech report |title=Uniform Resource Locators (URL) |author-first1=Tim |author-last1=Berners-Lee |author-link1=Tim Berners-Lee |author-first2=Larry |author-last2=Masinter |author-link2=Larry Masinter |author-first3=Mark Perry |author-last3=McCahill |author-link3=Mark Perry McCahill |date=October 1994 <!--|url=http://ds.internic.net/internet-drafts/draft-ietf-uri-url-08.txt-->}} (This Internet-Draft was published as a Proposed Standard RFC, {{harvp|RFC 1738|1994}}) Cited in {{cite tech report |title=Constituent Component Interface++ |author-first1=C. S. |author-last1=Ang |author-first2=D. C. |author-last2=Martin |publisher=UCSF Library and Center for Knowledge Management |date=January 1995 |url=https://listserv.heanet.ie/cgi-bin/wa?A2=ind9501&L=HTML-WG&P=R23201&X=C6F9505B05BC9A3B67 |access-date=2017-10-23  |archive-date=2017-10-23  |archive-url=https://web.archive.org/web/20171023231159/https://listserv.heanet.ie/cgi-bin/wa?A2=ind9501&L=HTML-WG&P=R23201&X=C6F9505B05BC9A3B67 |url-status=live }}</ref>  In his book ''[[Weaving the Web]]'', Berners-Lee emphasizes his preference for the original inclusion of "universal" in the expansion rather than the word "uniform", to which it was later changed, and he gives a brief account of the contention that led to the change.

==<span class="anchor" id="syntax"></span>Syntax==
{{main|Uniform Resource Identifier#Syntax}}
Every HTTP URL conforms to the syntax of a generic URI. {{#section:Uniform resource identifier|syntax}}<!-- see Help:LST for how this works -->

A web browser will usually [[Uniform Resource Identifier#Resolution|dereference]] a URL by performing an [[Hypertext Transfer Protocol|HTTP]] request to the specified host, by default on port number 80. URLs using the <code>https</code> scheme require that requests and responses be made over a [[HTTPS|secure connection to the website]].

{{anchor|Internationalised URL}}

==Internationalized URL==
Internet users are distributed throughout the world using a wide variety of languages and alphabets, and expect to be able to create URLs in their own local alphabets. An [[Internationalized Resource Identifier]] (IRI) is a form of URL that includes [[Unicode]] characters.  All modern browsers support IRIs. The parts of the URL requiring special treatment for different alphabets are the domain name and path.{{sfnp|W3C|2008}}{{sfnp|W3C|2014}}

The domain name in the IRI is known as an [[Internationalized Domain Name]] (IDN). Web and Internet software automatically convert the domain name into [[punycode]] usable by the [[Domain Name System]]; for example, the Chinese URL <code><nowiki>http:</nowiki>//例子.卷筒纸</code> becomes <code><nowiki>http:</nowiki>//xn--fsqu00a.xn--3lr804guic/</code>. The <code>xn--</code> indicates that the character was not originally [[ASCII]].{{sfnp|IANA|2003}}

The URL path name can also be specified by the user in the local writing system. If not already encoded, it is converted to [[UTF-8]], and any characters not part of the basic URL character set are escaped as [[hexadecimal]] using [[percent-encoding]]; for example, the Japanese URL <code><nowiki> http:</nowiki>//example.com/引き割り.html</code> becomes <code><nowiki>http:</nowiki>//example.com/%E5%BC%95%E3%81%8D%E5%89%B2%E3%82%8A.html</code>. The target computer decodes the address and displays the page.{{sfnp|W3C|2008}}

=={{anchor|prurl}}Protocol-relative URLs==
<!--section is linked from other pages-->
Protocol-relative links (PRL), also known as protocol-relative URLs (PRURL), are URLs that have no protocol specified. For example, <code>//example.com</code> will use the protocol of the current page, typically HTTP or HTTPS.<ref>{{cite book |author-last=Glaser |author-first=J. D. |url={{GBurl|id=6u2sBAAAQBAJ|p=193}} |title=Secure Development for Mobile Apps: How to Design and Code Secure Mobile Applications with PHP and JavaScript |date=March 10, 2014 |publisher=[[CRC Press]] |isbn=978-1-48220903-7 |edition=1st |page=193 |language=en-US |access-date=12 October 2015}}</ref><ref>{{cite book |author-last=Schafer |author-first=Steven M. |url={{GBurl|id=DW0uyBZzEDwC|pg=PT124}} |title=HTML, XHTML, and CSS Bible |date=2011 |publisher=[[John Wiley & Sons]]|isbn=978-1-11808130-3 |edition=1st |page=124 |language=en-US |access-date=12 October 2015}}</ref>

==See also==
<!-- Please keep entries in alphabetical order & add a short description [[WP:SEEALSO]] -->
{{div col|colwidth=20em}}
* [[Hyperlink]]
* [[Persistent uniform resource locator|PURL]] – Persistent URL
* [[CURIE]] (Compact URI)
* [[URI fragment]]
* [[Internet resource locator]] (IRL)
* [[Internationalized Resource Identifier]] (IRI)
* [[Clean URL]]
* [[Typosquatting]]
* [[Uniform Resource Identifier]]
* [[URI normalization]]
* [[Slash (punctuation)#Networking|Use of slashes in networking]]
{{div col end}}
<!-- please keep entries in alphabetical order -->

==Notes==
{{notelist|30em}}

==Citations==
{{reflist|30em}}

==References==
{{refbegin|30em}}
* {{cite web |url=http://news.bbc.co.uk/1/hi/technology/8306631.stm |title=Berners-Lee "sorry" for slashes |publisher=[[BBC News]] |date=14 October 2009 |access-date=14 February 2010 |ref={{SfnRef|BBC News|2009}} |archive-date=2020-06-05  |archive-url=https://web.archive.org/web/20200605102245/http://news.bbc.co.uk/2/hi/technology/8306631.stm |url-status=live }}
* {{cite web |url=http://www.w3.org/Conferences/IETF92/WWX_BOF_mins.html |title=Living Documents BoF Minutes |publisher=[[World Wide Web Consortium]] |date=18 March 1992 |access-date=26 December 2011 |ref={{SfnRef|IETF|1992}} |archive-date=2012-11-22  |archive-url=https://web.archive.org/web/20121122075812/http://www.w3.org/Conferences/IETF92/WWX_BOF_mins.html |url-status=live }}                   
* {{cite web |url=http://www.w3.org/Addressing/URL/url-spec.txt |title=Uniform Resource Locators (URL): A Syntax for the Expression of Access Information of Objects on the Network |first=Tim |last=Berners-Lee |author-link=Tim Berners-Lee |date=21 March 1994 |publisher=[[World Wide Web Consortium]] |access-date=13 September 2015 |ref={{SfnRef|W3C|1994}} |archive-date=2015-09-09  |archive-url=https://web.archive.org/web/20150909152849/http://www.w3.org/Addressing/URL/url-spec.txt |url-status=live }}
* {{cite IETF |rfc=1738 |title=Uniform Resource Locators (URL) |author-first1=Tim |author-last1=Berners-Lee |author-link1=Tim Berners-Lee |author-first2=Larry |author-last2=Masinter |author-link2=Larry Masinter |author-first3=Mark Perry |author-last3=McCahill |author-link3=Mark Perry McCahill |date=December 1994 |access-date=31 August 2015 |ref={{SfnRef|RFC 1738|1994}}}}
* {{cite web |url=http://www.w3.org/People/Berners-Lee/FAQ.html#etc |author-first=Tim |author-last=Berners-Lee |author-link=Tim Berners-Lee |work=Frequently asked questions |title=Why the //, #, etc? |orig-year=2000 |date=2015 |publisher=[[World Wide Web Consortium]] |access-date=3 February 2010 |archive-date=2020-05-14  |archive-url=https://web.archive.org/web/20200514191316/https://www.w3.org/People/Berners-Lee/FAQ.html#etc |url-status=live }}
* {{cite web |url=http://www.w3.org/html/wg/href/draft#url |title=Web addresses in HTML 5 |editor-first1=Daniel "Dan" |editor-last1=Connolly |editor-link1=Daniel Connolly (computer scientist) |editor-first2=C. Michael |editor-last2=Sperberg-McQueen |editor-link2=C. Michael Sperberg-McQueen |date=21 May 2009 |publisher=[[World Wide Web Consortium]] |access-date=13 September 2015 |ref={{SfnRef|W3C|2009}} |archive-date=2015-07-10  |archive-url=https://web.archive.org/web/20150710151425/http://www.w3.org/html/wg/href/draft#url |url-status=live }}
* {{cite web |url=http://www.atm.tut.fi/list-archive/ietf-announce/msg13572.html |archive-url=https://web.archive.org/web/20041208124351/http://www.atm.tut.fi/list-archive/ietf-announce/msg13572.html |archive-date=8 December 2004 |title=Completion of IANA Selection of IDNA Prefix |author=IANA |work=IETF-Announce mailing list |date=14 February 2003 |access-date=3 September 2015 |author-link=Internet Assigned Numbers Authority }}
* {{cite IETF |rfc=1866|section=8.2.1 |title=Hypertext Markup Language – 2.0 |author-first1=Tim |author-last1=Berners-Lee |author-link1=Tim Berners-Lee |author-first2=Daniel "Dan" |author-last2=Connolly |author-link2=Daniel Connolly (computer scientist) |publisher=[[Internet Engineering Task Force]] |date=November 1995 |s2cid=6628570 |access-date=13 September 2015 |ref={{SfnRef|RFC 1866|1995}} |website=IETF Datatracker }}
* {{cite IETF |rfc=2396 |title=Uniform Resource Identifiers (URI): Generic Syntax |author-first1=Tim |author-last1=Berners-Lee |author-link1=Tim Berners-Lee |author-first2=Roy T. |author-last2=Fielding |author-link2=Roy T. Fielding |author-first3=Larry |author-last3=Masinter |author-link3=Larry Masinter |date=August 1998 |access-date=31 August 2015 |ref={{SfnRef|RFC 2396|1998}}}}
* {{cite IETF |rfc=7595 |title=Guidelines and Registration Procedures for URI Schemes |editor-first=Dave |editor-last=Thaler |author-first1=Tony |author-last1=Hansen |author-first2=Ted |author-last2=Hardie |date=June 2015 |ref={{SfnRef|IETF|2015}}}}
* {{cite IETF |rfc=3305 |title=Report from the Joint W3C/IETF URI Planning Interest Group: Uniform Resource Identifiers (URIs), URLs, and Uniform Resource Names (URNs): Clarifications and Recommendations |editor-first1=Michael |editor-last1=Mealling |editor-link1=Michael Mealling |editor-first2=Ray |editor-last2=Denenberg |date=August 2002 |access-date=13 September 2015 |ref={{SfnRef|Joint W3C/IETF URI Planning Interest Group|2002}}}}
* {{cite IETF |rfc=3986 |title=Uniform Resource Identifiers (URI): Generic Syntax |author-first1=Tim |author-last1=Berners-Lee |author-link1=Tim Berners-Lee |author-first2=Roy T. |author-last2=Fielding |author-link2=Roy T. Fielding |author-first3=Larry |author-last3=Masinter |author-link3=Larry Masinter |date=January 2005 |access-date=31 August 2015 |ref={{SfnRef|RFC 3986|2005}}}}
* {{cite IETF |rfc=3986 |title=Uniform Resource Identifiers (URI): Generic Syntax |section=3|sectionname= Syntax Components |author-first1=Tim |author-last1=Berners-Lee |author-link1=Tim Berners-Lee |author-first2=Roy T. |author-last2=Fielding |author-link2=Roy T. Fielding |author-first3=Larry |author-last3=Masinter |author-link3=Larry Masinter |date=January 2005 |access-date=31 August 2015 |ref={{SfnRef|RFC 3986, section 3|2005}} }} 
* {{cite web |title=An Introduction to Multilingual Web Addresses |date=9 May 2008 |url=http://www.w3.org/International/articles/idn-and-iri/ |access-date=11 January 2015 |ref={{SfnRef|W3C|2008}} |archive-date=2015-01-05  |archive-url=https://web.archive.org/web/20150105041451/http://www.w3.org/International/articles/idn-and-iri/ |url-status=live }}
* {{cite web |title=What is Happening with "International URLs" |author-first=A. |author-last=Phillip |url=https://www.w3.org/International/wiki/IRIStatus |publisher=[[World Wide Web Consortium]] |date=2014 |access-date=11 January 2015 |ref={{SfnRef|W3C|2014}} |archive-date=2015-02-17  |archive-url=https://web.archive.org/web/20150217192459/https://www.w3.org/International/wiki/IRIStatus |url-status=live }}
* {{cite web |last1=Lawrence |first1=Eric |date=2014-03-06 |title=Browser Arcana: IP Literals in URLs |url=https://docs.microsoft.com/en-us/archive/blogs/ieinternals/browser-arcana-ip-literals-in-urls |website=Microsoft Learn |access-date=22 June 2020 |url-status=live |archive-url=https://web.archive.org/web/20200622181648/https://docs.microsoft.com/en-us/archive/blogs/ieinternals/browser-arcana-ip-literals-in-urls |archive-date=22 June 2020 }}
{{refend}}

==External links==
* [https://url.spec.whatwg.org/ URL specification] at [[WHATWG]]
* [https://slevithan.github.io/parseuri/demo/ URL splitter] that splits any URI into its parts

{{Hypermedia}}
{{Authority control}}

[[Category:URL| ]]
[[Category:Identifiers]]
[[Category:Internet properties established in 1994]]