Type A and Type B
All USB hosts and devices have sockets, and all USB cables have plugs at both ends. The sockets on a host are Type A, and the sockets on peripheral devices are Type B or Mini-B (see below). Hubs have both Type A and Type B sockets because they function as a host to their devices as well as a device to the computer.
USB Plugs and Sockets
Type B sockets are on printers and external devices such as disk drives, while Mini-B sockets are on PDAs, cameras and other portables. The two versions of Mini-B are distinguishable by their outer shells. Mini-A is the small counterpart of Type A, but not widely used.
Sockets on a Hub
This Belkin hub, which plugs into a wall outlet for power, is connected to the computer by a Mini-B/Type A cable. It provides four Type A ports for peripherals, netting out to only three extra, because one Type A port on the computer is used to connect the hub.
USB-based Land Warrior
Not your ordinary computer, the Land Warrior is a body-worn system that uses USB as its "personal network." Developed by Pacific Consultants, its USB controller was created by TransDimension. (Image courtesy of the U.S. Department of Defense.)
Learn more about USB