Uninstall provides you with the ability to restore an upgrade to the previous Windows operating system you were using. This feature only applies if you are upgrading your computer from Windows 98 and Windows Millennium. It provides you with the ability to uninstall at any point during setup.
UPS
Uninterrupted Power Supply. Provides both surge protection and emergency backup power to connected equipment. The backup power allows users to work uninterrupted during power outages and to save critical files and properly shut down a computer until power is restored. Depending on the device, the backup power can last from ten minutes to an hour or more.
USB cable
A Universal Serial Bus cable attaches peripherals (such as printers, handhelds, copiers, scanners, etc.) to a USB port, located in the back of most computers. USB port connections are faster than parallel, serial, or SCSI port connections, and are therefore becoming standard on new computers and peripheral devices.
USB network adapter
Can be used as an alternative to a Network Interface Card to help network a desktop or laptop computer. A USB network adapter will provide slightly slower networking speeds than a Network Interface Card, but, unlike a PCI card for desktops, it doesn't require installation.
USB port
Universal Serial Bus port. Located in the back of most computers, the USB port is where peripherals such as keyboards, mice, modems, digital cameras, and some multifunction machines, printers, and scanners connect to a computer. Devices connect to USB ports via a USB cable.