Editing HTTP (section)

{{Short description|Application layer protocol}}
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{{Infobox protocol
| image       = HTTP logo.svg
| standard    = {{indented plainlist|
* {{IETF RFC|1945}} HTTP/1.0
* {{IETF RFC|9110}} HTTP Semantics
* {{IETF RFC|9111}} HTTP Caching
* {{IETF RFC|9112}} HTTP/1.1
* {{IETF RFC|9113}} [[HTTP/2]]
* {{IETF RFC|7541}} HTTP/2: HPACK Header Compression
* {{IETF RFC|8164}} HTTP/2: Opportunistic Security for HTTP/2
* {{IETF RFC|8336}} HTTP/2: The ORIGIN HTTP/2 Frame
* {{IETF RFC|8441}} HTTP/2: Bootstrapping WebSockets with HTTP/2
* {{IETF RFC|9114}} [[HTTP/3]]
* {{IETF RFC|9204}} HTTP/3: QPACK: Field Compression
}}
| developer   = Initially [[CERN]]; [[IETF]], [[W3C]]
| introdate   = {{Start date and age|1991|df=yes}}
| newer       =
|website={{URL|https://httpwg.org/specs/}}}}
{{HTTP}}
{{IPstack}}

'''HTTP''' ('''Hypertext Transfer Protocol''') is an [[application layer]] protocol in the [[Internet protocol suite]] model for distributed, collaborative, [[hypermedia]] information systems.<ref name="rfc9110" /> HTTP is the foundation of data communication for the [[World Wide Web]], where [[hypertext]] documents include [[hyperlink]]s to other resources that the user can easily access, for example by a [[Computer mouse|mouse]] click or by tapping the screen in a [[web browser]].

Development of HTTP was initiated by [[Tim Berners-Lee]] at [[CERN]] in 1989 and summarized in a simple document describing the behavior of a client and a server using the first HTTP version, named 0.9.<ref name="HTTP/0.9-specifications">{{Cite web|url=https://www.w3.org/pub/WWW/Protocols/HTTP/AsImplemented.html|title=The Original HTTP as defined in 1991|website=www.w3.org|publisher=World Wide Web Consortium|date=1991-01-01|access-date=2010-07-24|language=en|author=Tim Berner-Lee}}</ref> That version was subsequently developed, eventually becoming the public 1.0.<ref name="HTTP/1.0-first-unofficial-draft">{{Cite web|url=https://www.w3.org/Protocols/HTTP/HTTP2.html|title=Basic HTTP as defined in 1992|website=www.w3.org|publisher=World Wide Web Consortium|year=1992|access-date=2021-10-19|language=en|author=Tim Berner-Lee}}</ref>

Development of early HTTP [[Requests for Comments]] (RFCs) started a few years later in a coordinated effort by the [[Internet Engineering Task Force]] (IETF) and the [[World Wide Web Consortium]] (W3C), with work later moving to the IETF.

HTTP/1 was finalized and fully documented (as version 1.0) in 1996.<ref>In {{IETF RFC|1945}}. That specification was then overcome by HTTP/1.1.</ref>  It evolved (as version 1.1) in 1997 and then its specifications were updated in 1999, 2014, and 2022.<ref>{{IETF RFC|2068}} (1997) was obsoleted by {{IETF RFC|2616}} in 1999, which was obsoleted by {{IETF RFC|7230}} in 2014, which was obsoleted by {{IETF RFC|9110}} in 2022.</ref> Its secure variant named [[HTTPS]] is used by more than 85% of websites.<ref name="HTTPS-usage-web-servers">{{Cite web|title=Usage Statistics of Default protocol https for websites|url=https://w3techs.com/technologies/details/ce-httpsdefault|access-date=2024-01-05|website=w3techs.com}}</ref> 

[[HTTP/2]], published in 2015, provides a more efficient expression of HTTP's semantics "on the wire". {{As of|2024|08|post=,}} it is supported by 66.2% of websites<ref name="HTTP2-usage-web-servers">{{Cite web|title=Usage Statistics of HTTP/2 for websites|url=https://w3techs.com/technologies/details/ce-http2|access-date=2024-01-05|website=w3techs.com}}</ref><ref>{{Cite web |title=Usage Statistics of HTTP/3 for Websites, August 2024 |url=https://w3techs.com/technologies/details/ce-http3 |access-date=2024-08-13 |website=w3techs.com}}</ref> (35.3% HTTP/2 + 30.9% HTTP/3 with backwards compatibility) and supported by almost all web browsers (over 98% of users).<ref name="HTTP2-Can-I-Use">{{Cite web|title=Can I use... Support tables for HTML5, CSS3, etc|url=https://caniuse.com/?search=http2|access-date=2024-01-05|website=caniuse.com}}</ref> It is also supported by major web servers over [[Transport Layer Security]] (TLS) using an [[Application-Layer Protocol Negotiation]] (ALPN) extension<ref name="rfc7301">{{cite ietf|rfc=7301|title=Transport Layer Security (TLS) Application-Layer Protocol Negotiation Extension|date=July 2014|publisher=IETF|doi=10.17487/RFC7301 |last1=Friedl |first1=S. |last2=Popov |first2=A. |last3=Langley |first3=A. |last4=Stephan |first4=E. }}</ref> where [[TLS 1.2]] or newer is required.<ref>{{cite web|url=https://http2.github.io/http2-spec/#TLSUsage|title=Hypertext Transfer Protocol Version 2, Use of TLS Features|last1=Belshe|first1=M.|last2=Peon|first2=R.|access-date=2015-02-10|last3=Thomson|first3=M.|archive-date=2013-07-15|archive-url=https://web.archive.org/web/20130715004452/https://http2.github.io/http2-spec/#TLSUsage|url-status=dead}}</ref><ref>{{Cite ietf|first=David|last=Benjamin|title=Using TLS 1.3 with HTTP/2|rfc=8740|access-date=2020-06-02|quote=This lowers the barrier for deploying TLS 1.3, a major security improvement over TLS 1.2.}}</ref>

[[HTTP/3]], the successor to HTTP/2, was published in 2022.<ref>{{cite ietf|title=HTTP/3 |date=6 June 2022 |rfc=9114 |access-date=2022-06-06}}</ref> {{As of|2024|02|post=,}} it is now used on 30.9% of websites<ref name="HTTP3-usage-web-servers">{{Cite web|title=Usage Statistics of HTTP/3 for websites|url=https://w3techs.com/technologies/details/ce-http3|access-date=2024-01-08|website=w3techs.com}}</ref> and is supported by most web browsers, i.e. (at least partially) supported by 97% of users.<ref name="HTTP3-Can-I-Use">{{Cite web|title=Can I use... Support tables for HTML5, CSS3, etc|url=https://caniuse.com/?search=http3|access-date=2024-01-08|website=canIuse.com}}</ref> HTTP/3 uses [[QUIC]] instead of [[Transmission Control Protocol|TCP]] for the underlying transport protocol. Like HTTP/2, it does not obsolete previous major versions of the protocol. Support for HTTP/3 was added to [[Cloudflare]] and [[Google Chrome]] first,<ref>{{cite web|url=https://www.zdnet.com/article/cloudflare-google-chrome-and-firefox-add-http3-support/|title=Cloudflare, Google Chrome, and Firefox add HTTP/3 support|website=ZDNet|date=26 September 2019|access-date=27 September 2019|df=dmy-all|first=Catalin|last=Cimpanu}}</ref><ref>{{Cite web|url=https://blog.cloudflare.com/http3-the-past-present-and-future/|title=HTTP/3: the past, the present, and the future|date=2019-09-26|website=The Cloudflare Blog|language=en|access-date=2019-10-30}}</ref> and is also enabled in [[Firefox]].<ref>{{cite web |url=https://community.cloudflare.com/t/firefox-nightly-supports-http-3/127778 |title=Firefox Nightly supports HTTP 3 – General – Cloudflare Community |date=2019-11-19 |access-date=2020-01-23}}</ref> HTTP/3 has lower latency for real-world web pages, if enabled on the server, and loads faster than with HTTP/2, in some cases over three times faster than HTTP/1.1 (which is still commonly only enabled).<!-- The article written before HTTP/3 standardization, but after OUIC standardized, and that part of the article (and the link there links to older standard: "0-RTT should not be blindly enabled. There are some possible security concerns depending on your threat model." --><ref>{{Cite web |title=HTTP/3 is Fast |url=https://requestmetrics.com/web-performance/http3-is-fast |access-date=2022-07-01 |website=Request Metrics |language=en}}</ref>