U
 

Uplink -- communication between an Earth-based transmitter and a satellite.

Universal Resource Locator (URL) -- an address you use to tell your browser where to find a particular Internet resource. For example, the URL for the WorldWide Language Institute is http://wwli.com.

Username -- the name assigned to a user of a computer network. Typing your username on the computer screen is part of the login procedure and identifies you to the computer system.