Editing USB (section)

== History ==
[[File:USB Icon.svg|thumb|upright=0.5|alt=Large circle is left end of horizontal line. The line forks into three branches ending in circle, triangle and square symbols.|The basic USB ''trident'' logo<ref>{{cite web | title = Icon design recommendation for Identifying USB 2.0 Ports on PCs, Hosts and Hubs | publisher = USB Implementers Forum | url = http://www.usb.org/developers/docs/icon_design.pdf | access-date = 26 April 2013 | archive-date = 3 October 2016 | archive-url = https://web.archive.org/web/20161003080319/http://www.usb.org/developers/docs/icon_design.pdf | url-status = live}}.</ref>]]

A group of seven companies began the development of USB in 1995:<ref>{{cite web |url=https://www.usb.org/members |title=Members |access-date=7 November 2021 |archive-date=7 November 2021 |archive-url=https://web.archive.org/web/20211107220855/https://www.usb.org/members |url-status=live}}</ref> [[Compaq]], [[Digital Equipment Corporation|DEC]], [[IBM]], [[Intel]], [[Microsoft]], [[NEC]], and [[Nortel]]. The goal was to make it fundamentally easier to connect external devices to PCs by replacing the multitude of connectors at the back of PCs, addressing the usability issues of existing interfaces, and simplifying software configuration of all devices connected to USB, as well as permitting greater data transfer rates for external devices and [[plug and play]] features.<ref>{{cite web|url=https://www.intel.com/content/www/us/en/standards/usb-two-decades-of-plug-and-play-article.html|title=Two decades of "plug and play": How USB became the most successful interface in the history of computing|access-date=14 June 2021|archive-date=15 June 2021|archive-url=https://web.archive.org/web/20210615025638/https://www.intel.com/content/www/us/en/standards/usb-two-decades-of-plug-and-play-article.html|url-status=live}}</ref> Concepts of the 1979 [[Atari SIO]] serial bus, of the 8-bit Atari computers, and the 1980 [[IEEE-488]] derived [[Commodore bus]], and Hewlett Packard's [[HP-IL]] bus pioneered this approach.<ref>{{cite news|last1=Stilphen|first1=Scott|title=DP Interviews ... Joe Decuir|url=http://www.digitpress.com/library/interviews/interview_joe_decuir.html|access-date=2 August 2017|publisher=Digit Press}}</ref><ref name=":Decuir2023">{{Cite web |last=Decuir |first=Joseph |date=Feb 2023 |title=IEEE – Three generations of animation machines: Atari and Amiga, Joe Decuir, IEEE Fellow UW Engineering faculty |url=https://vcfed.org/wp-content/uploads/2024/02/Joe_Decuir_VCF_West_2023_Slides.pdf |website=VCF – Vintage Computer Foundation}}</ref> A consortium led by Apple, and containing Sony, Panasonic (Matsushita), LG, Toshiba, Hitachi, Cannon, Philips Electronics, Compaq, Thomson and Texas Instruments, would develop the concept further, from 1986, as the [[IEEE 1394]] firewire standard and patent pool.<ref>{{Cite web |title=The Mac Observer – Apple, Sony, Phillips, Others Band Together On FireWire Patent Pool |url=https://www.macobserver.com/news/99/february/990217/firewirealliance.html |access-date=2025-02-10 |website=www.macobserver.com}}</ref> [[Joseph C. Decuir]], originally of Atari, then Commodore, and a designer of the Atari SIO common bus, would work on the USB project, for Microsoft, obtaining one of the related US patents.<ref>{{Cite patent|number=US5781028A|title=System and method for a switched data bus termination|gdate=1998-07-14|invent1=Decuir|inventor1-first=Joseph C.|url=https://patents.google.com/patent/US5781028A/en?inventor=Joseph+C.+Decuir}}</ref> [[Ajay Bhatt]] and his team{{Efn|Bhatt's team at Intel included Bala Sudarshan Cadambi, Jeff Morriss, Shaun Knoll, and Shelagh Callahan.<ref>{{cite web |url=https://www.allaboutcircuits.com/news/king-of-plug-and-play-how-usb-took-the-world-by-storm/ |author=Biljana Ognenova |date=2022-02-22|title=The King of Plug-and-Play: How USB Took the World by Storm |website=allaboutcircuits.com|access-date=2025-04-01}}</ref>}} worked on the standard at Intel;<ref>{{cite web | url = http://www.intel.com/pressroom/kits/bios/abhatt.htm | title = Intel Fellow: Ajay V. Bhatt | publisher = [[Intel Corporation]] | url-status=dead | archive-url = https://web.archive.org/web/20091104041719/http://www.intel.com/pressroom/kits/bios/abhatt.htm | archive-date = 4 November 2009}}</ref><ref>{{cite web |url= http://www.oregonlive.com/business/index.ssf/2009/05/intel_ad_campaign_remakes_rese.html |title= Intel ad campaign remakes researchers into rock stars |first= Mark |last= Rogoway |work= [[The Oregonian]] |date= 9 May 2009 |access-date= 23 September 2009 |url-status=live |archive-url= https://web.archive.org/web/20090826081315/http://www.oregonlive.com/business/index.ssf/2009/05/intel_ad_campaign_remakes_rese.html |archive-date= 26 August 2009}}</ref> the first [[integrated circuit]]s supporting USB were produced by Intel in 1995.<ref name="1394_2_4">{{cite book |editor-first = Hui |editor1-last = Pan |editor2-first = Paul |editor2-last = Polishuk |title = 1394 Monthly Newsletter |url = https://books.google.com/books?id=fRvbxgH4wmsC&pg=PA7 |access-date = 23 October 2012 |publisher = Information Gatekeepers |pages = 7–9 |id = GGKEY:H5S2XNXNH99 |url-status=live |archive-url = https://web.archive.org/web/20121112184629/http://books.google.com/books?id=fRvbxgH4wmsC&pg=PA7 |archive-date = 12 November 2012}}</ref>

=== USB 1.''x'' <span class="anchor" id="1.0"></span><span class="anchor" id="1.1"></span><span class="anchor" id="1.x"></span><span class="anchor" id="LS"></span><span class="anchor" id="FS"></span> ===
[[File:Certified USB.svg|thumb|upright=0.5|The Basic-Speed USB logo]]
Released in January 1996, USB&nbsp;1.0 specified signaling rates of 1.5&nbsp;Mbit/s (''Low Bandwidth'' or ''Low Speed'') and 12&nbsp;Mbit/s (''Full Speed'').<ref>{{cite tech report | title=Universal Serial Bus Specification | number=v1.0 | year=1996 | section=4.2.1 | page=29 | url=https://fl.hw.cz/docs/usb/usb10doc.pdf | url-status=live | archive-url=https://web.archive.org/web/20180130144424/https://fl.hw.cz/docs/usb/usb10doc.pdf | archive-date=30 January 2018}}</ref> It did not allow for extension cables, due to timing and power limitations. Few USB devices made it to the market until USB&nbsp;1.1 was released in August 1998. USB&nbsp;1.1 was the earliest revision that was widely adopted and led to what Microsoft designated the "[[Legacy-free PC]]".<ref name="Macworld iMac">{{cite web |url=http://www.macworld.com/article/135017/2008/08/imacanniversary.html |title=Eight ways the iMac changed computing |work=Macworld |date=15 August 2008 |access-date=5 September 2017 |url-status=live |archive-url=https://web.archive.org/web/20111222091746/http://www.macworld.com/article/135017/2008/08/imacanniversary.html |archive-date=22 December 2011 }}</ref><ref name="BusinessWeek iMac">{{cite web | work = Business week | year = 1999 | url = http://www.businessweek.com/1999/99_50/c3659057.htm | title = The PC Follows iMac's Lead | url-status=dead | archive-url = https://web.archive.org/web/20150923221417/http://www.businessweek.com/1999/99_50/c3659057.htm | archive-date = 23 September 2015}}</ref><ref name="Popular Mechanics iMac">{{cite journal|title=Popular Mechanics: Making Connections|journal = Popular Mechanics Magazine|url=https://books.google.com/books?id=R9MDAAAAMBAJ&pg=PA59|date=February 2001|publisher=Hearst Magazines|page=59|issn=0032-4558|url-status=live|archive-url=https://web.archive.org/web/20170215084550/https://books.google.com/books?id=R9MDAAAAMBAJ&pg=PA59|archive-date=15 February 2017}}</ref>

Neither USB 1.0 nor 1.1 specified a design for any connector smaller than the standard type A or type B. Though many designs for a miniaturized type B connector appeared on many peripherals, conformity to the USB&nbsp;1.''x'' standard was hampered by treating peripherals that had miniature connectors as though they had a tethered connection (that is: no plug or receptacle at the peripheral end). There was no known miniature type A connector until USB&nbsp;2.0 (revision 1.01) introduced one.

=== USB 2.0 <span class="anchor" id="2.0"></span><span class="anchor" id="2.0HS"></span><span class="anchor" id="HS"></span><span class="anchor" id="62680-1"></span>===
[[File:Certified Hi-Speed USB.svg|thumb|upright=0.5|The Hi-Speed USB logo]]

USB&nbsp;2.0 was released in April 2000, adding a higher maximum signaling rate of 480&nbsp;Mbit/s (maximum theoretical data throughput 53&nbsp;MByte/s<ref name="throughput2.0">{{cite web |url= https://microchipdeveloper.com/usb:high-speed |title= High Speed USB Maximum Theoretical Throughput |date= 23 March 2021 | publisher= Microchip Technology Incorporated |url-status=live |archive-url= https://web.archive.org/web/20210326115716/https://microchipdeveloper.com/usb:high-speed |archive-date= 26 March 2021 | access-date=23 March 2021}}</ref>) named ''High Speed'' or ''High Bandwidth'', in addition to the USB&nbsp;1.''x'' ''Full Speed'' signaling rate of 12&nbsp;Mbit/s (maximum theoretical data throughput 1.2&nbsp;MByte/s).<ref name="throughput1.1">{{cite web |url= https://microchipdeveloper.com/usb:full-speed |title= Full Speed USB Maximum Theoretical Throughput |date= 23 March 2021 | publisher= Microchip Technology Incorporated |url-status=live |archive-url= https://web.archive.org/web/20210326115653/https://microchipdeveloper.com/usb:full-speed |archive-date= 26 March 2021 | access-date=23 March 2021}}</ref>

Modifications to the USB specification have been made via [[Engineering change order|engineering change notices]] (ECNs). The most important of these ECNs are included into the USB&nbsp;2.0 specification package available from USB.org:<ref>{{cite web |url= http://www.usb.org/developers/docs/usb20_docs/ |title= USB 2.0 Specification |publisher= USB Implementers Forum |url-status=dead |archive-url= https://web.archive.org/web/20171203144114/http://www.usb.org/developers/docs/usb20_docs/ |archive-date= 3 December 2017 |access-date=28 April 2019 }}</ref>

* ''Mini-A and Mini-B Connector''
* ''Micro-USB Cables and Connectors Specification 1.01''
* ''[[InterChip USB]] Supplement''
* ''On-The-Go Supplement 1.3'' [[USB On-The-Go]] makes it possible for two USB devices to communicate with each other without requiring a separate USB host
* ''[[USB hardware#USB battery charging|Battery Charging]] Specification 1.1'' Added support for dedicated chargers, host chargers behavior for devices with dead batteries
* ''Battery Charging Specification 1.2'':<ref name="battchargespec1.2">{{cite web |url=http://www.usb.org/developers/docs/devclass_docs/BCv1.2_070312.zip |title=Battery Charging v1.2 Spec and Adopters Agreement |date=7 March 2012 |publisher=USB Implementers Forum |format=ZIP |url-status=live |archive-url=https://web.archive.org/web/20141006113700/http://www.usb.org/developers/docs/devclass_docs/BCv1.2_070312.zip |archive-date=6 October 2014 |access-date=13 May 2021  }}</ref> with increased current of 1.5&nbsp;A on charging ports for unconfigured devices, allowing high-speed communication while having a current up to 1.5&nbsp;A
* ''Link Power Management Addendum ECN'', which adds a ''sleep'' power state

=== USB 3.''x'' <span class="anchor" id="3.0"></span><span class="anchor" id="SS"></span><span class="anchor" id="3.x"></span>===
{{Main|USB 3.0}}
[[File:Certified SuperSpeed USB Logo.svg|thumb|upright=0.5|Deprecated SuperSpeed USB logo]]

The USB&nbsp;3.0 specification was released on 12 November 2008, with its management transferring from USB&nbsp;3.0 Promoter Group to the USB Implementers Forum (USB-IF) and announced on 17 November 2008 at the SuperSpeed USB Developers Conference.<ref name="ReferenceA">{{Cite press release | url= http://www.usb.org/press/USB-IF_Press_Releases/2008_11_17_USB_IF.pdf | title= USB 3.0 Specification Now Available | location= San Jose, Calif. | website = USB Implementers Forum | date= 17 November 2008 | access-date= 22 June 2010 | archive-url= https://web.archive.org/web/20100331035202/http://www.usb.org/press/USB-IF_Press_Releases/2008_11_17_USB_IF.pdf | archive-date= 31 March 2010}}</ref>

USB&nbsp;3.0 adds a new architecture and protocol named ''SuperSpeed'', with associated [[backward-compatible]] plugs, receptacles, and cables. SuperSpeed plugs and receptacles are identified with a distinct logo and blue inserts in standard format receptacles.

The SuperSpeed architecture provides for an operation mode at a rate of 5.0&nbsp;Gbit/s, in addition to the three existing operation modes. Its efficiency is dependent on a number of factors including physical symbol encoding and link-level overhead. At a 5&nbsp;Gbit/s signaling rate with [[8b/10b encoding]], each byte needs 10 bits to transmit, so the raw throughput is 500&nbsp;MB/s. When flow control, packet framing and protocol overhead are considered, it is realistic for about two-thirds of the raw throughput, or 330&nbsp;MB/s to transmit to an application.<ref name=USB30Spec/>{{rp|at=4–19}} SuperSpeed's architecture is [[full-duplex]]; all earlier implementations, USB 1.0-2.0, are all half-duplex, arbitrated by the host.<ref>{{cite web |url=http://www8.hp.com/h20195/v2/GetDocument.aspx?docname=4AA4-2724ENW |title=USB 3.0 Technology |year=2012 |access-date=2 January 2014 |publisher=[[Hewlett-Packard|HP]] |format=PDF |url-status=live |archive-url=https://web.archive.org/web/20150219151039/http://www8.hp.com/h20195/v2/GetDocument.aspx?docname=4AA4-2724ENW |archive-date=19 February 2015}}</ref>

Low-power and high-power devices remain operational with this standard, but devices implementing SuperSpeed can provide an increased current of between 150&nbsp;mA and 900&nbsp;mA, by discrete steps of 150&nbsp;mA.<ref name=USB30Spec/>{{rp|at=9–9}}

USB 3.0 also introduced the [[USB Attached SCSI|USB Attached SCSI Protocol (UASP)]], which provides generally faster transfer speeds than the BOT (Bulk-Only-Transfer) protocol.

[[USB 3.0#USB 3.1|USB&nbsp;3.1]],<ref name=USB31Spec/> released in July 2013 has two variants. The first one preserves USB&nbsp;3.0's ''SuperSpeed'' architecture and protocol and its operation mode is newly named ''USB&nbsp;3.1 Gen 1'',<ref name="USB 3.1 language usage 2015-05">{{cite web |date= 2015-05-28|title=USB 3.1 Specification Language Usage Guidelines from USB-IF |url=http://www.usb.org/developers/ssusb/USB_3_1_Language_Product_and_Packaging_Guidelines_FINAL.pdf  |publisher = USB Implementers Forum  |url-status=dead |archive-url=https://web.archive.org/web/20160312135950/http://www.usb.org/developers/ssusb/USB_3_1_Language_Product_and_Packaging_Guidelines_FINAL.pdf |archive-date=12 March 2016 }}</ref>
<ref name="USB 3.1 language usage 2018-08">{{cite web |author=<!-- not stated -->|date=2018-08-27 |title=USB 3.1 Specification Language Usage Guidelines from USB-IF |url=https://www.usb.org/sites/default/files/usb_3_1_language_product_and_packaging_guidelines_final_0.pdf |publisher=USB Implementers Forum |url-status=live |archive-url=https://web.archive.org/web/20190625163256/https://www.usb.org/sites/default/files/usb_3_1_language_product_and_packaging_guidelines_final_0.pdf|archive-date = 2019-06-25
|access-date=2025-04-02}}</ref><ref>{{cite web |url=https://www.msi.com/blog/usb-3-1-gen1-gen2-explained |title=USB 3.1 Gen 1 & Gen 2 explained |author=Silvia |website=www.msi.org |date=5 August 2015 |access-date=5 April 2018 |archive-date=8 July 2018 |archive-url=https://web.archive.org/web/20180708020201/https://www.msi.com/blog/usb-3-1-gen1-gen2-explained |url-status=live }}</ref> and the second version introduces a distinctively new ''SuperSpeedPlus'' architecture and protocol with a second operation mode named as ''USB&nbsp;3.1 Gen 2'' (marketed as ''SuperSpeed+ USB''). SuperSpeed+ doubles the maximum signaling rate to 10&nbsp;Gbit/s (later marketed as ''SuperSpeed USB 10&nbsp;Gbps'' by the USB&nbsp;3.2 specification), while reducing line encoding overhead to just 3% by changing the [[encoding scheme]] to [[128b/132b]].<ref name="USB 3.1 language usage 2015-05"/><ref>{{cite web |url=http://www.usb.org/developers/docs/usb_31_102214.zip |archive-url=https://web.archive.org/web/20141121225502/http://www.usb.org/developers/docs/usb_31_102214.zip |title=Universal Serial Bus 3.1 Specification |publisher=USB Implementers Forum |date=26 July 2013 |access-date=19 November 2014 |archive-date=21 November 2014 |via=Usb.org |format=ZIP}}</ref>

[[USB 3.0#USB 3.2|USB&nbsp;3.2]], released in September 2017,<ref name=USB32Spec>{{Cite web |url=https://www.usb.org/document-library/usb-32-specification-released-september-22-2017-and-ecns |title=The USB 3.2 Specification released on September 22, 2017 and ECNs |date=22 September 2017 |website=usb.org |access-date=4 September 2019 |archive-date=6 July 2019 |archive-url=https://web.archive.org/web/20190706231129/https://www.usb.org/document-library/usb-32-specification-released-september-22-2017-and-ecns|url-status=live}}</ref> preserves existing USB&nbsp;3.1 ''SuperSpeed'' and ''SuperSpeedPlus'' architectures and protocols and their respective operation modes, but introduces two additional ''SuperSpeedPlus'' operation modes (''USB&nbsp;3.2 Gen&nbsp;1×2'' and ''USB&nbsp;3.2 Gen&nbsp;2×2'') with the new [[USB-C]] Fabric with signaling rates of 10 and 20&nbsp;Gbit/s (raw data rates of 1212 and 2424&nbsp;MB/s). The increase in bandwidth is a result of two-lane operation over existing wires that were originally intended for flip-flop capabilities of the USB-C connector.<ref>{{Cite press release |url=http://www.usb.org/press/USB_3.2_PR_USB-IF_Final.pdf |title=USB 3.0 Promoter Group Announces USB 3.2 Update |date=25 July 2017 | website = USB Implementers Forum |location=Beaverton, Oregon, US |access-date=27 July 2017 |archive-date=21 September 2017 |archive-url=https://web.archive.org/web/20170921191940/http://www.usb.org/press/USB_3.2_PR_USB-IF_Final.pdf |url-status=live}}</ref>

==== Naming scheme ====
Starting with the USB 3.2 specification, USB-IF introduced a new naming scheme.<ref name="USB 3.2 language usage 2018-10">{{Cite web|url=https://www.usb.org/sites/default/files/usb_3_2_language_product_and_packaging_guidelines_final.pdf |title=USB 3.2 Specification Language Usage Guidelines from USB-IF|date=3 Oct 2018 |website= USB Implementers Forum|url-status=live |access-date=4 September 2019 |archive-date=3 November 2021|archive-url=https://web.archive.org/web/20211103022718/https://www.usb.org/sites/default/files/usb_3_2_language_product_and_packaging_guidelines_final.pdf}}</ref> To help companies with the branding of the different operation modes, USB-IF recommended branding the 5, 10, and 20&nbsp;Gbit/s capabilities as ''SuperSpeed USB 5Gbps'', ''SuperSpeed USB 10&nbsp;Gbps'', and ''SuperSpeed USB 20&nbsp;Gbps'', respectively.<ref>{{Cite web|last=Ravencraft|first=Jeff|url=https://www.usb.org/sites/default/files/D1T2-1%20-%20USB%20Branding%20Session.pdf|title=USB DevDays 2019 – Branding Session|date=19 November 2019|website=USB Implementers Forum|pages=16|type=Presentation|access-date=22 March 2020|archive-url=https://web.archive.org/web/20200322121822/https://www.usb.org/sites/default/files/D1T2-1%20-%20USB%20Branding%20Session.pdf|archive-date=22 March 2020}}</ref>

In 2023, they were replaced again,<ref name="USB data performance language usage 2024-01">{{cite web |date=22 Jan 2024 |title=USB Data Performance Language Usage Guidelines from USB-IF |url=https://www.usb.org/sites/default/files/usb_data_performance_language_usage_guidelines_jan_2024.pdf |website=USB Implementers Forum |url-status=live |archive-url=https://web.archive.org/web/20241126185424/https://www.usb.org/sites/default/files/usb_data_performance_language_usage_guidelines_jan_2024.pdf |archive-date=2024-11-26 |access-date=2025-04-02}}</ref> removing ''"SuperSpeed"'', with ''USB 5Gbps'', ''USB 10Gbps'', and ''USB 20Gbps''. With new ''Packaging'' and ''Port'' logos.<ref name="USB licensed marks">{{cite web |date=September 20, 2023 |title=USB-IF Licensed Mark(s) Requirements |url=https://www.usb.org/sites/default/files/trademark_license_agreement_licensed_mark_requirements_final_as_of_september_20_2023.pdf |website=USB Implementers Forum |url-status=live |archive-url=https://web.archive.org/web/20250311155445/https://www.usb.org/sites/default/files/trademark_license_agreement_licensed_mark_requirements_final_as_of_september_20_2023.pdf |archive-date=2025-03-11 |access-date=2025-04-02}}</ref>

=== USB4<span class="anchor" id="USB4"></span>===
{{Update|section|date=August 2024|reason=Incomplete, erroneous and not up-to-date; e.g. lacks differences between USB4 first version and 2.0. Applies also to main article.}}
{{main|USB4}}
[[File:Certified USB4 40Gbps Logo.svg|thumb|upright=0.5|Deprecated ''Certified USB4'' logo]]

The USB4 specification was released on 29 August 2019 by the USB Implementers Forum.<ref name=USB4Spec>{{Cite web |url=https://www.usb.org/sites/default/files/USB4%20Specification.zip |title=USB Promoter Group USB4 Specification |date=29 August 2019 |website=USB Implementers Forum |access-date=30 August 2019 |archive-date=13 February 2021 |archive-url=https://web.archive.org/web/20210213071426/https://www.usb.org/sites/default/files/USB4%20Specification.zip |url-status=live}}</ref>

The USB4 2.0 specification was released on 1 September 2022 by the USB Implementers Forum.<ref>{{Cite web |title=USB Promoter Group Announces USB4 Version 2.0 Specification defines delivering up to 80&nbsp;Gbps over USB Type-C |url=https://www.usb.org/sites/default/files/2022-09/USB%20PG%20USB4%20Version%202.0%2080Gbps%20Announcement_FINAL.pdf}}</ref>

USB4 is based on the [[Thunderbolt 3]] protocol.<ref>{{Cite web|url=https://arstechnica.com/gadgets/2019/03/thunderbolt-3-becomes-usb4-as-intels-interconnect-goes-royalty-free/|title=Thunderbolt 3 becomes USB4, as Intel's interconnect goes royalty-free|last=Bright|first=Peter|date=4 March 2019|website=Ars Technica|access-date=4 March 2019|archive-date=13 February 2021|archive-url=https://web.archive.org/web/20210213071427/https://arstechnica.com/gadgets/2019/03/thunderbolt-3-becomes-usb4-as-intels-interconnect-goes-royalty-free/|url-status=live}}</ref> It supports 40&nbsp;Gbit/s throughput, is compatible with Thunderbolt 3, and backward compatible with USB&nbsp;3.2 and USB&nbsp;2.0.<ref>{{Cite web|url=https://www.cnet.com/news/usb4-marries-thunderbolt-3-for-faster-speeds-and-smarter-transfers/|title=USB4 Marries Thunderbolt 3 for Faster Speeds and Smarter Transfers |last=Grunin|first=Lori|website=CNET|date=4 March 2019|access-date=4 March 2019|archive-date=4 March 2019|archive-url=https://web.archive.org/web/20190304232454/https://www.cnet.com/news/usb4-marries-thunderbolt-3-for-faster-speeds-and-smarter-transfers/|url-status=live}}</ref><ref>{{Cite web|url=https://www.pcmag.com/news/366931/thunderbolt-3-merges-with-usb-to-become-usb4|title=Thunderbolt 3 Merges With USB to Become USB4|last=Brant|first=Tom|date=4 March 2019|website=PC Magazine|access-date=4 March 2019|archive-date=5 March 2019|archive-url=https://web.archive.org/web/20190305024642/https://www.pcmag.com/news/366931/thunderbolt-3-merges-with-usb-to-become-usb4|url-status=live}}</ref> The architecture defines a method to share a single high-speed link with multiple end device types dynamically that best serves the transfer of data by type and application.

During [[CES 2020]], USB-IF and Intel stated their intention to allow USB4 products that support all the optional functionality as [[Thunderbolt 4]] products.

USB4&nbsp;2.0 with 80&nbsp;Gbit/s speeds was to be revealed in November 2022.<ref>{{Cite web|url=https://www.pcgamer.com/usb4-version-20-with-80gbps-speeds-is-coming/|title=USB4 Version 2.0 with 80Gbps speeds is coming|last=Szewczyk|first=Chris|date=September 5, 2022|website=PC Gamer|access-date=September 20, 2024}}</ref><ref>{{Cite press release|url=https://www.usb.org/sites/default/files/2022-09/USB%20PG%20USB4%20Version%202.0%2080Gbps%20Announcement_FINAL.pdf|last1=Saunders|first1=Brad|last2=Balich|first2=Joe|title=USB Promoter Group Announces USB4® Version 2.0|date=September 1, 2022|publisher=USB Implementers Forum|location=Beaverton, OR, USA|access-date=September 20, 2024}}</ref> Further technical details were to be released at two USB developer days scheduled for November 2022.<ref>{{Cite press release|url=https://usb.org/sites/default/files/2022-10/USB-IF%20USB%2080Gbps%20Announcement_FINAL_v2.pdf|last=Balich|first=Joe|title=USB-IF Announces Publication of New USB4® Specification to Enable USB 80Gbps Performance|date=October 18, 2022|publisher=USB Implementers Forum|location=Beaverton, OR, USA|access-date=September 20, 2024}}</ref>{{update inline|date=October 2024}}

The USB4 specification states that the following technologies shall be supported by USB4:<ref name=USB42Spec/>
{{clear}}
{| class="wikitable"
|-
! rowspan="2" style="width:240px" | Connection
! colspan="3" | Mandatory for
! rowspan="2" | Remarks
|-
! style="width:50px; text-align:center"| host !! style="width:50px; text-align:center"| hub !! style="width:50px; text-align:center"| device
|-
| '''USB 2.0''' (480&nbsp;Mbit/s)|| {{yes}} || {{yes}} || {{yes}} || Contrary to other functions – which use the multiplexing of high-speed links – USB 2.0 over USB-C utilizes its own differential pair of wires.
|-
| '''Tunneled USB 3.2 Gen 2×1''' (10&nbsp;Gbit/s)|| {{yes}} || {{yes}} || {{no}} ||
|-
| '''Tunneled USB 3.2 Gen 2×2''' (20&nbsp;Gbit/s)|| {{no}} || {{no}} || {{no}} ||
|-
| '''Tunneled USB&nbsp;3 Gen T''' (5–80&nbsp;Gbit/s)|| {{no}} || {{no}} || {{no}} || A type of USB&nbsp;3 Tunneling architecture where the Enhanced SuperSpeed System is extended to allow operation at the maximum bandwidth available on the USB4 Link.
|-
| '''USB4 Gen 2''' (10 or 20&nbsp;Gbit/s) || {{yes}} || {{yes}} || {{yes}} || rowspan="2"| Either one or two lanes
|-
| '''USB4 Gen 3''' (20 or 40&nbsp;Gbit/s) || {{no}} || {{yes}} || {{no}}
|-
| '''Tunneled DisplayPort 1.4a''' || {{yes}} || {{yes}} || {{no}} ||The specification requires that hosts and hubs support the DisplayPort Alternate Mode.
|-
| '''Tunneled PCI Express 3.0''' || {{no}} || {{yes}} || {{no}} || The PCI Express function of USB4 replicates the functionality of previous versions of the [[Thunderbolt (interface)|Thunderbolt]] specification.
|-
| '''Host-to-Host communications''' || {{yes}} || {{yes}} || {{n/a}} || A LAN-like connection between two peers
|-
| '''Thunderbolt 3 Alternate Mode''' || {{no}} || {{yes}} || {{no}} || Thunderbolt 3 uses cables with USB‑C plugs; the USB4 specification allows hosts and devices, and requires hubs, to support interoperability with the standard using the Thunderbolt 3 Alternate Mode (namely DisplayPort and PCIe).
|-
| '''Other Alternate Modes'''|| {{no}} || {{no}} || {{no}}
| USB4 products may optionally offer interoperability with the [[HDMI]], [[Mobile High-Definition Link|MHL]], and [[VirtualLink]] Alternate Modes.
|}

==== September 2022 naming scheme ====
[[File:USB 2022 September naming scheme.svg|thumb|upright=2.8|An overview of USB naming scheme that was put in place in September 2022
<br />(A mix of USB specifications and their marketing names are being displayed<br />because specifications are sometimes wrongly used as marketing names.){{Disputed inline|File:USB 2022 September naming scheme.svg|for=USB4 20&nbsp;Gbit/s does not exist; USB4 2×2 is not interchangeable with USB 3.2 2×2 as<br />indicated by the logo; logos for USB 3.x and USB4 are different.|date=July 2023}}]]
Because of the previous confusing naming schemes, USB-IF decided to change it once again. As of 2 September 2022, marketing names follow the syntax "USB&nbsp;''x''Gbps", where ''x'' is the speed of transfer in Gbit/s.<ref name="USB data performance language usage 2022-09">{{Cite web|title=USB Data Performance Language Usage Guidelines from USB-IF|url=https://usb.org/sites/default/files/usb_data_performance_language_usage_guidelines_september_2022.pdf|website = USB Implementers Forum | access-date=2 September 2022|archive-date=1 October 2022|archive-url=https://web.archive.org/web/20221001115816/https://www.usb.org/sites/default/files/usb_data_performance_language_usage_guidelines_september_2022.pdf|url-status=dead}}</ref> Overview of the updated names and logos can be seen in the adjacent table.

The operation modes USB&nbsp;3.2&nbsp;Gen&nbsp;2×2 and USB4&nbsp;Gen&nbsp;2×2 – or: USB&nbsp;3.2&nbsp;Gen&nbsp;2×1 and USB4&nbsp;Gen&nbsp;2×1 – are not interchangeable or compatible; all participating controllers must operate with the same mode.

=== Version history <span class="anchor" id="0.6e"></span><span class="anchor" id="0.7"></span><span class="anchor" id="0.8"></span><span class="anchor" id="0.9"></span><span class="anchor" id="0.99"></span><span class="anchor" id="1.0RC"></span> ===

==== Release versions ====
{| class="wikitable sortable"
|-
! scope="row" | Name
! scope="row" | Release date
! scope="row" | Maximum signaling rate
! scope="row" | Note
|-
! scope="row" | {{Nowrap|USB 0.7}}
| {{Dts|November 1994}}
| {{dunno}}
| rowspan="4" | Pre-release
|-
! scope="row" | {{Nowrap|USB 0.8}}
| {{Dts|December 1994}}
| {{dunno}}
|-
! scope="row" | {{Nowrap|USB 0.9}}
| {{Dts|April 1995}}
| {{Nowrap|12&nbsp;Mbit/s: Full Speed (FS)}}
|-
! scope="row" | {{Nowrap|USB 0.99}}
| {{Dts|August 1995}}
| {{dunno}}
|-
! scope="row" | {{Nowrap|USB 1.0-RC}}
| {{Dts|November 1995}}
| {{dunno}}
| Release Candidate
|-
! scope="row" | {{Nowrap|USB 1.0}}
| {{Dts|January 1996}}
| rowspan=2|{{Nowrap|1.5&nbsp;Mbit/s: Low Speed (LS)}}<br />{{Nowrap|12&nbsp;Mbit/s: Full Speed (FS)}}
| rowspan="2" | Renamed to ''Basic-Speed''
|-
! scope="row" | {{Nowrap|USB 1.1}}
| {{Dts|September 1998}}
|-
! scope="row" | {{Nowrap|USB 2.0}}
| {{Dts|April 2000}}
| {{Nowrap|480&nbsp;Mbit/s: High Speed (HS)}}
|
|-
! scope="row" | {{Nowrap|USB 3.0}}
| {{Dts|November 2008}}
| {{Nowrap|5&nbsp;Gbit/s: SuperSpeed (SS)}}
| Renamed to ''USB&nbsp;3.1 Gen&nbsp;1'',<ref name="USB 3.1 language usage 2015-05"/> and later to ''USB&nbsp;3.2 Gen&nbsp;1×1''
|-
! scope="row" | {{Nowrap|USB 3.1}}
| {{Dts|July 2013}}
| {{Nowrap|10&nbsp;Gbit/s: SuperSpeed+ (SS+)}}
| Renamed to ''USB&nbsp;3.1 Gen&nbsp;2'',<ref name="USB 3.1 language usage 2015-05"/> and later to ''USB&nbsp;3.2 Gen&nbsp;2×1''
|-
! scope="row" | {{Nowrap|USB 3.2}}
| {{Dts|August 2017}}
| {{Nowrap|20&nbsp;Gbit/s: SuperSpeed+ two-lane}}
| Adds a second full-duplex lane for data exchange, noted as ''×2'': ''USB&nbsp;3.2 Gen&nbsp;1×2'' and ''Gen&nbsp;2×2''. This requires full-featured [[USB-C]] cables and USB&nbsp;3.2 fabric.<ref>{{cite web |title=USB 3.2 explained: Making sense of current and confusing USB standards |url=https://www.cnet.com/tech/mobile/usb-3-2-explained-making-sense-of-current-and-confusing-usb-standard/ |author=Matt Elliot |date=11 March 2019|website=CNET |access-date=26 July 2022 |url-status=live |archive-url=https://web.archive.org/web/20210707230329/https://www.cnet.com/tech/mobile/usb-3-2-explained-making-sense-of-current-and-confusing-usb-standard/|archive-date=7 July 2021 }}</ref>
|-
! scope="row" | {{Nowrap|USB4}}
| {{Dts|August 2019}}
| {{Nowrap|40&nbsp;Gbit/s: two-lane}}
| Includes new ''USB4 Gen&nbsp;2×2'' (64b/66b encoding) and ''Gen&nbsp;3×2'' (128b/132b encoding) modes and introduces USB4 routing for tunneling of USB&nbsp;3.2, DisplayPort&nbsp;1.4a and PCI Express traffic and host-to-host transfers, based on the Thunderbolt&nbsp;3 protocol. Requires USB4 Fabric.
|-
! scope="row" | {{Nowrap|USB4 2.0}}
| {{Dts|September 2022}}
| {{Nowrap|120&nbsp;⇄ 40&nbsp;Gbit/s: asymmetric}}
| Includes new ''USB4 Gen&nbsp;4×2'' (PAM-3 encoding) mode to get 80 and 120&nbsp;Gbit/s over Type-C connector.<ref>{{cite web | url=https://www.usb.org/document-library/usb4r-specification-v20 | title=USB4 Specification v2.0 &#124; USB-IF }}</ref> Requires USB4 Fabric.
|}

==== Power-related standards <span class="anchor" id="PD"></span>====
{| class="wikitable sortable"
|-
! style="width:16em;" | Release name
! Release date
! style="width:8em;" | Max. power
! Note
|-
| [[USB Battery Charging]] Rev. 1.0
| 2007-03-08
| 7.5&nbsp;W (5&nbsp;V, 1.5&nbsp;A)
|
|-
| USB Battery Charging Rev. 1.1
| 2009-04-15
| 7.5&nbsp;W (5&nbsp;V, 1.5&nbsp;A)
|Page 28, Table 5–2, but with limitation on paragraph 3.5. In ordinary USB 2.0's Standard-A port, 1.5&nbsp;A only.<ref>{{Cite web|url=https://usb.org/document-library/battery-charging-v11-spec-and-adopters-agreement|title=Battery Charging v1.1 Spec and Adopters Agreement|website=USB.org|access-date=31 July 2019|archive-date=11 January 2021|archive-url=https://web.archive.org/web/20210111005750/https://usb.org/document-library/battery-charging-v11-spec-and-adopters-agreement|url-status=dead}}</ref>
|-
| USB Battery Charging Rev. 1.2
| 2010-12-07
| 7.5&nbsp;W (5&nbsp;V, 1.5&nbsp;A)
|<ref>{{Cite web|url=https://usb.org/document-library/battery-charging-v12-spec-and-adopters-agreement|title=Battery Charging v1.2 Spec and Adopters Agreement|website=USB.org|access-date=31 July 2019|archive-date=31 July 2019|archive-url=https://web.archive.org/web/20190731150826/https://usb.org/document-library/battery-charging-v12-spec-and-adopters-agreement|url-status=live}}</ref>
|-
| [[USB hardware#USB power delivery|USB Power Delivery]] Rev. 1.0 (V. 1.0)
| 2012-07-05
| 100&nbsp;W (20&nbsp;V, 5&nbsp;A)
| Using FSK protocol over bus power (V{{sub|BUS}})
|-
| USB Power Delivery Rev. 1.0 (V. 1.3)
| 2014-03-11
| 100&nbsp;W (20&nbsp;V, 5&nbsp;A)
| 
|-
| USB Type-C Rev. 1.0
| 2014-08-11
| 15&nbsp;W (5&nbsp;V, 3&nbsp;A)
| New connector and cable specification
|-
| USB Power Delivery Rev. 2.0 (V. 1.0)
| 2014-08-11
| 100&nbsp;W (20&nbsp;V, 5&nbsp;A)
| Using BMC protocol over communication channel (CC) on USB-C cables
|-
| USB Type-C Rev. 1.1
| 2015-04-03
| 15&nbsp;W (5&nbsp;V, 3&nbsp;A)
|
|-
| USB Power Delivery Rev. 2.0 (V. 1.1)
| 2015-05-07
| 100&nbsp;W (20&nbsp;V, 5&nbsp;A)
|
|-
| USB Type-C Rev. 1.2
| 2016-03-25
| 15&nbsp;W (5&nbsp;V, 3&nbsp;A)
|
|-
| USB Power Delivery Rev. 2.0 (V. 1.2)
| 2016-03-25
| 100&nbsp;W (20&nbsp;V, 5&nbsp;A)
|
|-
| USB Power Delivery Rev. 2.0 (V. 1.3)
| 2017-01-12
| 100&nbsp;W (20&nbsp;V, 5&nbsp;A)
|
|-
| USB Power Delivery Rev. 3.0 (V. 1.1)
| 2017-01-12
| 100&nbsp;W (20&nbsp;V, 5&nbsp;A)
|
|-
| USB Type-C Rev. 1.3
| 2017-07-14
| 15&nbsp;W (5&nbsp;V, 3&nbsp;A)
|
|-
| USB Power Delivery Rev. 3.0 (V. 1.2)
| 2018-06-21
| 100&nbsp;W (20&nbsp;V, 5&nbsp;A)
| 
|-
| USB Type-C Rev. 1.4
| 2019-03-29
| 15&nbsp;W (5&nbsp;V, 3&nbsp;A)
|
|-
| USB Type-C Rev. 2.0
| 2019-08-29
| 15&nbsp;W (5&nbsp;V, 3&nbsp;A)
| Enabling USB4 over USB Type-C connectors and cables.
|-
| USB Power Delivery Rev. 3.0 (V. 2.0)
| 2019-08-29
| 100&nbsp;W (20&nbsp;V, 5&nbsp;A)
|<ref>{{Cite web|url=https://www.usb.org/document-library/usb-power-delivery-0|title=USB Power Delivery|website=USB.org|access-date=3 September 2019|archive-date=3 September 2019|archive-url=https://web.archive.org/web/20190903163400/https://www.usb.org/document-library/usb-power-delivery-0|url-status=live}}</ref>
|-
| USB Power Delivery Rev. 3.1 (V. 1.0)
| 2021-05-24
| 240&nbsp;W (48&nbsp;V, 5&nbsp;A)
|
|-
| USB Type-C Rev. 2.1
| 2021-05-25
| 15&nbsp;W (5&nbsp;V, 3&nbsp;A)
|<ref>{{Cite web|url=https://usb.org/document-library/usb-type-cr-cable-and-connector-specification-revision-21|title=USB Type-C Cable and Connector Specification Revision 2.1|website=USB.org|access-date=27 May 2021|archive-date=27 May 2021|archive-url=https://web.archive.org/web/20210527135133/https://usb.org/document-library/usb-type-cr-cable-and-connector-specification-revision-21|url-status=live}}</ref>
|-
| USB Power Delivery Rev. 3.1 (V. 1.1)
| 2021-07-06
| 240&nbsp;W (48&nbsp;V, 5&nbsp;A)
|<ref name="USB Power Delivery">{{Cite web|url=https://usb.org/document-library/usb-power-delivery|title=USB Power Delivery|website=USB.org|access-date=27 May 2021|archive-date=27 May 2021|archive-url=https://web.archive.org/web/20210527151756/https://usb.org/document-library/usb-power-delivery|url-status=live}}</ref>
|-
| USB Power Delivery Rev. 3.1 (V. 1.2)
| 2021-10-26
| 240&nbsp;W (48&nbsp;V, 5&nbsp;A)
| Including errata through October 2021<ref name="USB Power Delivery"/>
This version incorporates the following ECNs:
* Clarify use of Retries
* Battery Capabilities
* FRS timing problem
* PPS power rule clarifications
* Peak current support for EPR AVS APDO
|}