A USB (Universal Serial Bus) is a type of computer interface for connecting peripherals such as keyboard, mouse, printers, and external hard drives. USB is a plug-and-play technology, meaning that no additional software or drivers need to be installed to use a USB device. USB cables have a rectangular plug on one end that connects to a computer, and a smaller rectangular plug on the other end that connects to the peripheral device. USB has evolved over the years, with the latest version being USB 4.0, which offers faster speeds and improved power management compared to previous versions. USB is widely used in computers, consumer electronics, and mobile devices.