Universal Serial Bus (USB) is a standard that defines the cables, connectors, and communications protocols used in a bus for connection, communication, and power supply between various electronic/computing devices. Some of the key features of USB are listed on this slide. It is a host controlled communication protocol, i.e. USB allows only one host and multiple devices per bus. USB also supports multiple data transmission speeds. It has evolved from USB 1.1 to USB 3.0. With the exception of USB 3.0, which uses eight wires, USB uses a four-wire interface. One of the cool features of USB is external hot-swapping/ plug-and-play that allows end-users to connect and disconnect from the host while the bus is powered on. USB offers a low-cost data transmission and communication alternative because of the reasons discussed. Wireless USB can be used for wireless data transmission.