Short for Universal Serial Bus, it is a external bus standard that was designed to replace serial and parallel ports USB supports `Plug and Play installation of devices. A single USB port can connect up to 127 peripheral devices.
The original USB Version 1.1 has a top data transfer rate of 12Mbits/sec.
USB 2.0 (also referred to as Hi-Speed USB) was developed to reflect the higher data speeds needed for newer technologies. USB 2.2 has a higher data transfer rate of 480Mbps and is fully compatible with USB 1.1; it even uses the same connector and cable types.