UDP (User Datagram Protocol) - UDP is a core component of the Internet Protocol suite. Like TCP, UDP is used with IP, however, UDP is connectionless and does not guarantee reliable communication; the application itself must process any errors and check for reliable delivery. It is used in place of TCP when a reliable delivery is not required such as with streaming audio and video, DNS, online gaming, VOIP, SNMP, RIP, etc.
Unicast - the sending of information packets to a single network node. This type of network transmission is used where a private or unique resource such as media servers are being requested for two way connections that are needed to complete the network communication. So in the media server example, a client system may make the request for streaming content from the single source and the responding system may leverage unicast as part of the response to the session request to deliver the content.
URL (Uniform Resource Locator) - As the name indicates, a URL is an address used to give the location of a resource on the web. The first part is the ‘service descriptor’ which identifies the protocol being used (in the diagram it is HTTP). The ‘//’ indicates the start of path (the root directory) which is followed by the domain name. The remainder of the address is the directory path on the server that specifies the location of the file to be fetched. You may have noticed that when you visit a domain, the complete path is not displayed. For example, if you visit our home page at http://www.mcmcse.com, there is no file specified after the domain name.
USB (Universal Serial Bus) - A plug-and-play interface between a computer and peripherals (such as keyboards, scanners, printers, digital cameras, etc). In some situations, it can also be used to network 2 computers directly together. USB devices are "hot-swappable" which means that a new device can be added or removed without having to shut down the computer. USB 2.0 can transmit data at speeds up to 480Mbps. When a lot of USB devices need to be connected to a computer, a USB hub can be used to handle the extra connections.
USB Flash Drive - See Flash Drives
USMT - The User State Migration Tool (USMT) 4.0, part of the Windows Automated Installation Kit (Windows AIK), is a command line-scriptable tool for migrating user state from one computer or operating system to another. It is designed for large-scale migrations whereas Windows Easy Transfer is for small-scale and individual transfers. USMT migrates files and settings between Microsoft Windows versions 2000, XP, Vista and Windows 7, and is useful in migrating user settings and files during OS upgrades. Migrations from 32-bit to 64-bit are supported, but from 64-bit to 32-bit are not supported by USMT.
UTP (Unshielded Twisted Pair) - It is a cable type that consists of two or more insulated conductors in which each pair of conductors are twisted around each other. Category 1 UTP cables are used for telephony connections. Category 3 and higher are used for Ethernet LAN connections. UTP is inexpensive and easy to work with. Category 5 / 5E & Cat 6 Cabling Tutorial and FAQ's