USB is a small, rectangular or square connector that can transfer data at a speed of up to 480 MB per second in its most recent version, 2.0 (v1 ran at 1.5 MB) you can use a USB hub to connect up to 127 different devices to one USB port. most computers come with two or four USB ports

os of the USB's most attractive features is called hot swapping. almost all USB devies an be attached to the computer and detected the the OS while the computer is powered on. many older devices and buses required a reboot for the OS to recognize the device