Universal serial bus (USB)
From The Glossary of Digital Photography
A hardware standard for connecting peripheral devices to computers. USB allows up to 127 devices to be connected to a single USB host controller. USB hubs can be installed so that multiple devices can be connected to one USB port. A higher-speed version of USB, called USB 2.0 (USB2), has also been created. A USB2 port can have either a USB or USB2 device plugged into it. Many digital media card readers use either a USB or USB2 port to make their connections. USB connects at a speed of up to 12 Mb/sec, and USB 2.0 connects at speeds up to 480 Mb/sec. Most devices do not reach the maximum speed. When a number of devices are connected through a hub, or a single connection, they must share the available bandwidth. When selecting a USB or USB 2.0 hub, be sure that it is suitable for the desired application and will not slow down data transfer. For example, a USB hub will operate at USB speeds rather than USB 2.0 speeds no matter which type of device is plugged into it.
