upgrade: A complete revision of a computer program that you use to replace the current program.

UPS: Uninterruptible power supply; basically, a power strip combined with a battery to keep your computer running for a short time when the power goes out.

USB: Universal Serial Bus; a computer connection that you can use to attach many different kinds of devices and peripherals to a computer.

User Account Control: A Vista safety option that protects you from accidentally making changes to your system that could have a negative effect on system performance or stability.

utility: A type of computer program that’s designed to help you manage the computer, or diagnose or fix problems.