Source : Free On-Line Dictionary of Computing

Universal Serial Bus
     
         (USB) An external {peripheral} interface
        {standard} for communication between a computer and external
        {peripherals} over an inexpensive cable using {biserial}
        transmission.
     
        USB is intended to replace existing {serial ports}, {parallel
        ports}, {keyboard}, and {monitor} connectors and be used with
        {keyboards}, {mice}, {monitors}, {printers}, and possibly some
        low-speed {scanners} and removable {hard drives}.  For faster
        devices existing {IDE}, {SCSI}, or emerging {FC-AL} or
        {FireWire} interfaces can be used.
     
        USB works at 12 Mbps with specific consideration for low cost
        peripherals.  It supports up to 127 devices and both
        {isochronous} and {asynchronous} data transfers.  Cables can
        be up to five metres long and it includes built-in power
        distribution for low power devices.  It supports {daisy
        chaining} through a tiered star multidrop topology.  A USB
        cable has a rectangular "Type A" plug at the computer end and
        a square "Type B" plug at the peripheral end.
     
        Before March 1996 Intel started to integrate the necessary
        logic into {PC} {chip sets} and encourage other manufacturers
        to do likewise.  It was widely available by 1997.  Later
        versions of {Windows 95} included support for it.  It was
        standard on {Macintosh} computers in 1999.
     
        {USB 2.0} is a much faster enhanced version.
     
        {usb.org (http://www.usb.org/)}.
     
        (2002-01-01)