User Datagram Protocol (UDP) is one of the protocols for data transfer that is part of the TCP/IP suite of protocols.
UNIX
A computer operating system. Unix is designed for simultaneous users it is a multi-user operating system and has TCP/IP built-in. It is also used on servers for Internet applications.
URL
Uniform Resource Locator (URL) is the addressing system used on the World Wide Web and other Internet resources.
USENET
Usenet is similar to a bulletin board as it features thousands of newsgroups.