U

UNIX
A multiuser, multitasking operation system. It can be installed into any computer for which a C compiler exists and can be compiled into many different machine languages. It can be modified and customized for the users own purposes.

UnSticky
To stop the effect of a "sticky" window moving with you between desktops.

Upgrade
The process of installing newer, faster versions of either hardware or software.

URL
Uniform Resource Locator. This is the address used to retrieve an Internet resource.

Username
Name used to gain access to a computer system. Often required in mulituser systems. Also known as your Login ID.