Redirected from: Universal Serial Bus
Definition: USB
(1) Short for "USB flash drive" or "USB port." See USB drive and USB port.
(2) (Universal Serial Bus) The most widely used hardware interface for attaching peripherals to a computer. USB designations use a letter and number, such as Type A 3.0. The letter is the connector type, and the number is the speed (all types are illustrated at the end of this definition). The latest Type C was designed to replace all previous connectors (see USB Type C).
Every Computer Has Type A
There are at least two Type A ports on laptops and four on desktops, while USB "hubs" provide even more (see below). After debuting in 1997, USB became the standard for connecting keyboards, mice, printers and external storage drives, eventually replacing the PC's serial and parallel ports and the Apple Desktop Bus on Macs (see serial port, parallel port and ADB).
Hot Swappable USB Drives
Supporting 127 peripherals, devices can be plugged and unplugged while the computer is on. This "hot swappable" feature, combined with easy-to-reach ports on every computer, gave rise to the ubiquitous USB drive for transport, although a manual "eject" is required (see USB drive). See PoweredUSB, USB device class, USB OTG, USB switch and USB toy.
USB Can Be Power Only
Type A and B Ports
(2) (Universal Serial Bus) The most widely used hardware interface for attaching peripherals to a computer. USB designations use a letter and number, such as Type A 3.0. The letter is the connector type, and the number is the speed (all types are illustrated at the end of this definition). The latest Type C was designed to replace all previous connectors (see USB Type C).
Every Computer Has Type A
There are at least two Type A ports on laptops and four on desktops, while USB "hubs" provide even more (see below). After debuting in 1997, USB became the standard for connecting keyboards, mice, printers and external storage drives, eventually replacing the PC's serial and parallel ports and the Apple Desktop Bus on Macs (see serial port, parallel port and ADB).
Hot Swappable USB Drives
Supporting 127 peripherals, devices can be plugged and unplugged while the computer is on. This "hot swappable" feature, combined with easy-to-reach ports on every computer, gave rise to the ubiquitous USB drive for transport, although a manual "eject" is required (see USB drive). See PoweredUSB, USB device class, USB OTG, USB switch and USB toy.
USB is also a power source for phones, tablets and other devices. This Chromecast streaming stick plugs into the TV's HDMI port but is powered from a USB port (see Chromecast). (Image courtesy of Google Inc.)
Host sockets are Type A, and peripheral sockets are B, C and Lightning. Eventually, Type C is expected to replace the Type A-B connection (see USB Type C). See USB hub, Mini USB, Micro USB, Lightning connector and USB OTG.
Transfer Rate
Version (Year) (Mbps)
USB 3.1 (2014) 9600
(see USB 3.1)
USB 3.0 SuperSpeed (2008) 4800
(see USB 3.0)
USB 2.0 Hi-Speed (2001) 480
USB 1.1 (1998) 1.5 & 12
(1.5 Mbps slow channel
for keyboards, mice, etc.)