A USB is a common computer port, which shorts for Universal Serial Bus and allows communication between a computer and peripheral or other devices. Universal Serial Bus:?It is a plug-and-play interface that allows a computer to communicate with peripheral and other devices. USB-connected devices cover a broad range; anything from keyboards and mice to music players and flash drives. The USB cable provides four pathways- two power conductors and two twisted signal conductors. So it's a four-wire shielded cable. A USB is intended to allow hot-swapping and enhance plug-and-play. Without having to restart the computer, plug-and-play makes it capable of operating the system to involuntarily discover and configure, and hot-swapping allows the replacement and removal of a new peripheral device. It can have synchronous or asynchronous data transmission. USB offers several different data transmission rates. For example:USB version 1 offers two types of speeds that work best for slow I/O devices: the speeds are 1. 5 Mb per second and 12 Mb per second. Hence USB is not just a synchronous serial data transmission method.