Universal Serial Bus; an interface standard for connecting computers and electronic devices for communication and charging.
It was released in 1996, and is being currently maintained by the USB Implementors Forum (USB IF). It has three generations, USB 1.x, USB 2 and USB 3. An USB 4 is predicted to middle 2019.
It is a master-slave protocol, supports plug & play, has transfer rate control and supports also power transfer.