technology used to connect computers (computer) with peripherals, or input/output devices (input/output device).

First introduced in 1995, the USB standard was developed by a number of American companies, including IBM (International Business Machines Corporation), Intel Corporation, and Microsoft Corporation, as a simpler way of connecting hardware to personal computers (personal computer) (PCs). Before USB technology a PC typically would have one or two serial ports, a parallel port, mouse and keyboard ports, and, in some cases, a joystick port. A USB port represented a standardized way to connect a wide range of devices while offering significant advantages in speed over other connection types.

Initially, adoption of USB technology was slow. Computer manufacturers were slow to add the ports to their systems before USB-capable devices were available, and manufacturers of peripheral devices likewise were slow to market USB products before the ports became standard on new computers. In addition, operating systems (operating system) had only minimal support when the technology was first introduced. The first generation of Apple Inc.'s iMac, introduced in 1998, changed this, however. By making a popular computer that used only USB ports, Apple essentially drove other manufacturers to adopt the standard. Since then most printers, scanners, keyboards, and even portable flash-memory drives have used USB.

USB technology saw a number of revisions since its inception. Each revision increased the connection's speed while staying backward-compatible with older revisions. Also, improved adapters allowed users to use USB ports to connect to older serial devices such as network switches.