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UART stands for Universal Asynchronous Receiver/Transmitter. It is an integrated circuit that operates as a transceiver that converts synchronous data stream to continuous streams for asynchronous communications.
UDP stands for User Datagram Protocol. This is a transport layer protocol for exchange of datagrams in the Internet suite of TCP/IP protocols. UDP along with TCP both use IP for delivery however, UDP does not guarantee delivery and does not use error correction. Basically UDP performs equivalent functions of CLTP.
UDP storm is a flood of UDP packets used to overwhelm a server. This is the most common type of denial of service attack.
Undirected information is sending out data without regard to who gets it. Usenet and mailing lists are undirected.
Undo refers to a command that is used in software applications to allow the user to go back incrementally to usually undo their last several actions. An undo icon is sometimes located on a toolbar or is available under the edit menu.
Unencrypted describes data that is not scrambled. Others who have access to the data will be able to immediately read it right away. Encrypted data must be decrypted to be deciphered by using a complementary algorithm or by a computer program that use brute processing force to crack the encryption algorithm.
Unformat for a hard drive or other storage device is to use a utility program to restore data on that drive that may have been inadvertently formatted and temporarily lost the previous data.
Unicast is the technique for sending a packet through from a single source to a single destination. Most IP datagrams are sent via unicast as opposed to multicast.
Uninterruptible power supply refers to an electrical system or component capable of supplying power during a power outage or power surge. To accomplish this the computer system needs to be able to switch to an alternative power supply, such as a back up battery.
UNIX is a powerful computer operating system developed by IBM® that was once only run on mainframe computers. Now many forms of UNIX including an open source flavor called Linux is available on many different computer hardware platforms.
Uploading is the act of transferring a file from one computer system to another over a network using a server application and a client application. The application is commonly an FTP, SFTP or HTTP service that resides on a server computer. The client is either an FTP program or web browser which can upload the file between systems and it resides on a client computer. When the file is uploaded it is sent from the client computer up to the server computer across the network. Upload is the opposite of download.
URI stands for Uniform Resource Identifier. This is an address to a resource on the network or the Internet. URI is a superset containing the more familiar Uniform Resource Locators. For instance, every resource on the web is a file accessible through a URI web address. This URI is associated with a unique IP address. URIs typically consist of three parts, the naming scheme of the mechanism used to access the resource, the machine hosting the resource and the resource itself given as a path. So a web site address starts with the HTTP protocol http://, the web server domain name www.whateversite.org, and the HTML document file index.htm. The whole URI would be http://www.whateversite.org/index.htm.
URL stands for Uniform Resource Locator. This is a subset of the more inclusive Uniform Resource Identifier and refers to basically the same thing, a resource address on the network. For instance, every resource on the web is a file accessible through a URI web address. This URI is then associated with a unique IP address. URLs typically consist of three parts, the naming scheme of the mechanism used to access the resource, the machine hosting the resource and the resource itself given as a path. So a web site address starts with the HTTP protocol http://, the web server domain name www.whateversite.org, and the HTML document file index.htm. The whole URL would be http://www.whateversite.org/index.htm.
Usenet is a collection of newsgroups located on the Internet using the NNTP protocol. It is analogous to historic BBS bulletin board where members can post notes or questions to other members and users of the newsgroup. The Usenet covers a myriad of topics. The newsgroups can provide comprehensive information on computers, software, the Internet and programming languages. There is no central authority for Usenet.
User refers to the person operating a computer system whether locally or remotely. A user usually has to login to a system and provide a username and password.
Username is the name that identifies the user to computer system. The username is given in conjunction with a password for the user to login to the system. Both the username and password are normally case sensitive.
User interface refers to all the features of a program that governs the way a user can interact with it. The user interface from the perspective of a programmer is accessible through the API.
User agent is the terminology used in the OSI network model for a client application that interprets HTML documents. The web browser is the most prevalent type of user agent used on the web. Other types of user agents include non-visual web browsers, web spiders, search engines and web robots. A definition of a user agent can be found in the RFCs.
Utilities are utilitarian software applications that generally perform operating system management functions.
UUCP stands for UNIX to UNIX Copy Program. A protocol for communication between programs connected UNIX systems for copying files.
UUENCODE stands for UNIX to UNIX ENCODE. It is a method for converting files from binary files to ASCII text files on UNIX computer systems so that they can be sent across the Internet via email.
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