In computing, a peripheral bus is a computer bus designed to support computer peripherals like printers and hard drives. The term is generally used to refer to systems that offer support for a wide variety of devices, like Universal Serial Bus, as opposed to those that are dedicated to specific types of hardware, like SATA. This usage is not universal, some definitions include any bus system that is not a system bus, including examples like PCI. Others treat PCI and similar systems as a third category, the expansion bus.