Universal Serial Bus (USB) is a serial bus standard to interface devices. A major component in the legacy-free PC, USB was designed to allow peripherals to be connected using a single standardised interface socket, to improve plug-and-play capabilities by allowing devices to be connected and disconnected without rebooting the computer (hot swapping). Other convenient features include powering low-consumption devices without the need for an external power supply and allowing some devices to be used without requiring individual device drivers to be installed.

The USB external bus standard supports data transfer rates of 12 Mbps (12 million bits per second). One USB port can connect up to 127 peripheral devices, such as keyboards, modems, and mice.. USB also supports hot plugging and Plug-and-Play installation.