UDF
(Universal Disk Format)
Standard CD-ROM and DVD file system designed to ensure consistency in optical media.
UDP
(User Datagram Protocol)
A communications method that uses the Internet Protocol (IP) to send a data unit (called a datagram) from one computer to another in a network. Network applications that have very small data units to exchange might use UDP rather than TCP.
UFS
(UNIX File System)
This volume format is used primarily by UNIX and UNIX-based operating systems.
UID
(User identification number)
The number used in multiuser operating systems to uniquely identify a user.
UNIX
Pronounced YEW-nihks. Nonproprietary operating system used on computers.
URL
(Uniform Resource Locator)
An address of a file or resource accessible on a network server, such as a website on the Internet or a shared volume on a local file server. The URL prefix determines the protocol used: HTTP, AFP, SMB, and so on.
USB
(Universal Serial Bus)
A serial interface between a computer and add-on devices.
Universal Access
Mac OS X accessibility software for improving human interface usability and functionality.