A “plug-and-play” interface between a computer and add-on devices (such as audio players, joysticks, keyboards, telephones, scanners and printers). With USB, a new device can be added to your computer without having to add an adapter card or even having to turn the computer off. The USB peripheral bus standard was developed by Compaq, IBM, DEC, Intel, Microsoft, NEC and Northern Telecom and the technology is available without charge for all computer and device vendors. USB supports a data speed of up to 480 megabits per second. This speed will accommodate a wide range of devices, including MPEG-2 video devices, data gloves and digitizers. It is anticipated that USB will easily accommodate plug-in telephones that use ISDN and digital PBXs. Since October 1996, the Windows operating systems have been equipped with USB drivers or special software designed to work with specific I/O device types. USB is integrated into Windows 98 and newer. Today, most new computers and peripheral devices are equipped with USB. A different "plug-and-play" standard, Firewire/IEEE 1394, is designed to support much higher data rates and devices such as video camcorders and digital videodisk (DVD) players. Both standards are expected to exist together, serving different device types.
USB has two major versions: USB 1.1 (old) and USB 2.0. USB peripherals can operate at three speeds:

* Low Speed - 1.5 Mbps
* High Speed - 12 Mbps
* Full Speed - 480 Mbps (USB 2.0 only)

This definition is in context to Computer Hardware. See more contextual defintions for USB.