Universal Serial Bus ( USB) is an industry standard that allows data exchange and delivery of power between many various types of electronics. It specifies its architecture, in particular its the physical interface, and communication protocols for data transfer and power delivery to and from hosts, such as personal computers, to and from peripheral devices, e.g. displays, keyboards, and mass storage devices, and to and from intermediate hubs, which multiply the number of a host's ports. [2] USB was originally designed to standardize the connection of peripherals to computers, replacing various interfaces such as serial ports, parallel ports, game ports, and ADB ports, [3] and prior versions of USB became commonplace on a wide range of devices, such as keyboards, mice, cameras, printers, scanners, flash drives, smartphones, game consoles, and power banks. [4] [5] It has evolved into a standard to replace virtually all common ports on computers, mobile devices, peripherals, power supplies, and manifold other small electronics. In the current standard the USB-C connector replaces the many various connectors for power (up to 240W), displays (e.g. DisplayPort, HDMI), and many other uses, as well as all previous USB connectors. Unlike other data buses (such as Ethernet), USB connections are directed; a host device has "downstream" facing ports that connect to the "upstream" facing ports of devices. Only downstream facing ports provide power; this topology was chosen to easily prevent electrical overloads and damaged equipment. Thus, USB cables have different ends: A and B, with different physical connectors for each. Each format has a plug and receptacle defined for each of the A and B ends. A USB cable, by definition, has a plug on each end—one A (or C) and one B (or C)—and the corresponding receptacle is usually on a computer or electronic device. The mini and micro formats may connect to an AB receptacle, which accepts either an A or a B plug, that plug determining the behavior of the receptacle. Matt Elliot (11 March 2019). "USB 3.2 explained: Making sense of current and confusing USB standards". CNET. Archived from the original on 7 July 2021 . Retrieved 26 July 2022. USB 3.2 Specification Language Usage Guidelines from USB-IF" (PDF). usb.org. 26 February 2019. Archived (PDF) from the original on 3 November 2021 . Retrieved 4 September 2019.

Parameter Values". Battery Charging Specification, Revision 1.2. USB Implementers Forum. 7 December 2010. p.45. Archived from the original on 28 March 2016 . Retrieved 29 March 2016. Full-featured USB-C 3.1 cables are electronically marked cables that contain a full set of wires and a chip with an ID function based on the configuration data channel and vendor-defined messages (VDMs) from the USB Power Delivery 2.0 specification. USB-C devices also support power currents of 1.5A and 3.0A over the 5V power bus in addition to baseline 900mA; devices can either negotiate increased USB current through the configuration line or they can support the full Power Delivery specification using both BMC-coded configuration line and legacy BFSK-coded V BUS line. [ citation needed] The initial versions of the USB standard specified connectors that were easy to use and that would have acceptable life spans; revisions of the standard added smaller connectors useful for compact portable devices. Higher-speed development of the USB standard gave rise to another family of connectors to permit additional data paths. All versions of USB specify cable properties; version 3. x cables include additional data paths. The USB standard included power supply to peripheral devices; modern versions of the standard extend the power delivery limits for battery charging and devices requiring up to 240 watts. USB has been selected as the standard charging format for many mobile phones, reducing the proliferation of proprietary chargers. a b "USB Promoter Group USB4 Specification". usb.org. 29 August 2019. Archived from the original on 13 February 2021 . Retrieved 30 August 2019.

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USB4 particularly supports the tunneling of the Thunderbolt 3 protocols, namely PCI Express (PCIe, load/store interface) and DisplayPort (display interface). USB4 also adds host-to-host interfaces. [2]

a b c d "USB 3.1 Specification– Language Usage Guidelines from USB-IF" (PDF). Archived (PDF) from the original on 12 March 2016 – via www.usb.org. Universal Serial Bus Specification (PDF) (Technical report). 1996. p.29. v1.0. Archived (PDF) from the original on 30 January 2018. Two USB3.0 Standard-A receptacles (left) and two USB2.0 Standard-A receptacles (right) on a computer's front panel The USB Device Working Group has laid out specifications for audio streaming, and specific standards have been developed and implemented for audio class uses, such as microphones, speakers, headsets, telephones, musical instruments, etc. The working group has published three versions of audio device specifications: [65] [66] USB Audio1.0, 2.0, and 3.0, referred to as "UAC" [67] or "ADC". [68]

Includes new USB4 Gen2×2 (64b/66b encoding) and Gen3×2 (128b/132b encoding) modes and introduces USB4 routing for tunneling of USB3.2, DisplayPort1.4a and PCI Express traffic and host-to-host transfers, based on the Thunderbolt3 protocol; requires USB4 Fabric. Because use of the USB logo is only permitted after compliance testing, the user can have confidence that a USB device will work as expected without extensive interaction with settings and configuration. USB 3.0 Specification Now Available" (PDF) (Press release). San Jose, Calif. 17 November 2008. Archived from the original (PDF) on 31 March 2010 . Retrieved 22 June 2010– via usb.org.

USB cables are limited in length, as the standard was intended for peripherals on the same table-top, not between rooms or buildings. However, a USB port can be connected to a gateway that accesses distant devices. USB Class Codes". 22 September 2018. Archived from the original on 22 September 2018 – via www.usb.org. Battery Charging Specification 1.1 Added support for dedicated chargers, host chargers behavior for devices with dead batteriesOVERVIEW OF USB BATTERY CHARGING REVISION 1.2 AND THE IMPORTANT ROLE OF ADAPTER EMULATORS" (PDF). maxim integrated. 2014. p.3. Archived (PDF) from the original on 4 July 2021 . Retrieved 12 August 2021. a b c "Universal Serial Bus 3.2 Specification" (ZIP) (Revision 1.1ed.). USB Implementers Forum. June 2022 . Retrieved 27 April 2023.

rpms/dfu-util: USB Device Firmware Upgrade tool". fedoraproject.org. 14 May 2014. Archived from the original on 8 September 2014 . Retrieved 8 September 2014. Barnatt, Christopher (25 September 2022). Explaining USB: From 1.0 to USB4 V2.0 (ExplainingComputers) (video). There are so-called cables with A plugs on both ends, which may be valid if the "cable" includes, for example, a USB host-to-host transfer device with two ports. [3] This is, by definition, a device with two logical B ports, each with a captive cable, not a cable with two A ends. Portable devices having a USB On-The-Go port may want to charge and access a USB peripheral simultaneously, yet having only a single port (both due to On-The-Go and space requirement) prevents this. Accessory charging adapters (ACA) are devices that provide portable charging power to an On-The-Go connection between host and peripheral. The Type-A plug. This plug has an elongated rectangular cross-section, inserts into a Type-A receptacle on a downstream port on a USB host or hub, and carries both power and data. Captive cables on USB devices, such as keyboards or mice, terminate with a Type-A plug.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. Shaikh, Roshan Ashraf (3 November 2020). "USB-IF releases final specification of Media Agnostic USB". tweaktown.com. Archived from the original on 15 March 2021 . Retrieved 21 July 2021. High Speed USB Maximum Theoretical Throughput". Microchip Technology Incorporated. 23 March 2021. Archived from the original on 26 March 2021 . Retrieved 23 March 2021. Castor-Perry, Kendall (October 2010). "Designing Modern USB Audio Systems". Cypress Semiconductor. Archived from the original on 5 May 2018 . Retrieved 4 May 2018.