Editing Uniform Resource Identifier (section)

=== URLs and URNs ===

A [[Uniform Resource Name]] (URN) is a URI that identifies a resource by name in a particular namespace. A URN may be used to talk about a resource without implying its location or how to access it. For example, in the [[International Standard Book Number]] (ISBN) system, ''<nowiki>ISBN</nowiki> 0-486-27557-4'' identifies a specific edition of the [[William Shakespeare]] play ''[[Romeo and Juliet]]''. The URN for that edition would be ''<nowiki>urn:isbn:0-486-27557-4</nowiki>''. However, it gives no information as to where to find a copy of that book.

A [[Uniform Resource Locator]] (URL) is a URI that specifies the means of acting upon or obtaining the representation of a resource, i.e. specifying both its primary access mechanism and network location. For example, the URL <code><nowiki>http://example.org/wiki/Main_Page</nowiki></code> refers to a resource identified as <code><nowiki>/wiki/Main_Page</nowiki></code>, whose representation is obtainable via the [[Hypertext Transfer Protocol]] (''http:'') from a network host whose [[domain name]] is <code><nowiki>example.org</nowiki></code>. (In this case, HTTP usually implies it to be in the form of [[HTML]] and related code. In practice, that is not necessarily the case, as HTTP allows specifying arbitrary formats in its header.)

A URN is analogous to a person's name, while a URL is analogous to their street address. In other words, a URN identifies an item and a URL provides a method for finding it.

Technical publications, especially standards produced by the IETF and by the W3C, normally reflect a view outlined in a [[W3C Recommendation]] of 30 July 2001, which acknowledges the precedence of the term URI rather than endorsing any formal subdivision into URL and URN. {{cquote|URL is a useful but informal concept: a URL is a type of URI that identifies a resource via a representation of its primary access mechanism (e.g., its network "location"), rather than by some other attributes it may have.<ref>{{cite web |last1=((URI Planning Interest Group, W3C/IETF)) |title=URIs, URLs, and URNs: Clarifications and Recommendations 1.0 |url=https://www.w3.org/TR/uri-clarification/ |website=www.w3.org |publisher=W3C/IETF |access-date=8 December 2020 |date=September 2001}}</ref>}}

As such, a URL is simply a URI that happens to point to a resource over a network.{{efn|A report published in 2002 by a joint W3C/IETF working group aimed to normalize the divergent views held within the IETF and W3C over the relationship between the various 'UR*' terms and standards. While not published as a full standard by either organization, it has become the basis for the above common understanding and has informed many standards since then.}}{{Ref RFC|3305}} However, in non-technical contexts and in software for the World Wide Web, the term "URL" remains widely used. Additionally, the term "web address" (which has no formal definition) often occurs in non-technical publications as a synonym for a URI that uses the ''http'' or ''https'' schemes. Such assumptions can lead to confusion, for example, in the case of XML namespaces that have a [[#Relation to XML namespaces|visual similarity to resolvable URIs]].

Specifications produced by the [[WHATWG]] prefer ''URL'' over ''URI'', and so newer HTML5 APIs use ''URL'' over ''URI''.<ref>{{cite web |title= 6.3. URL APIs elsewhere |url=https://url.spec.whatwg.org/#url-apis-elsewhere |date= 12 May 2025 |website=URL Standard }}</ref> {{cquote|Standardize on the term URL. URI and IRI [Internationalized Resource Identifier] are just confusing. In practice a single algorithm is used for both so keeping them distinct is not helping anyone. URL also easily wins the search result popularity contest.<ref>{{cite web |title=URL Standard: Goals |url=https://url.spec.whatwg.org/#goals}}</ref>}}

While most URI schemes were originally designed to be used with a particular [[protocol (computing)|protocol]], and often have the same name, they are semantically different from protocols. For example, the scheme ''http'' is generally used for interacting with [[web resource]]s using HTTP, but the scheme ''[[file URI scheme|file]]'' has no protocol.