In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in packets) to other hosts on an Internet Protocol (IP) network. Within an IP network, UDP does not require prior communication to set up communication channels or data paths.

<protocol> (UDP) Internet standard network layer, transport layer and session layer protocols which provide simple but unreliable datagram services. UDP is defined in STD 6, RFC 768. It adds a checksum and additional process-to-process addressing information [to what?]. UDP is a connectionless protocol which, like TCP, is layered on top of IP. UDP neither guarantees delivery nor does it require a connection. As a result it is lightweight and efficient, but all error processing and retransmission must be taken care of by the application program. Unix manual page: udp(4). [Postel, Jon, User Datagram Protocol, RFC 768, Network Information Center, SRI International, Menlo Park, Calif., August 1980]. (1998-02-11)

Wireless Datagram Protocol (WDP) defines the movement of information from receiver to the sender and resembles the User Datagram Protocol in the Internet protocol suite.

UDP-Lite (Lightweight User Datagram Protocol) is a connectionless protocol that allows a potentially damaged data payload to be delivered to an application rather than being discarded by the receiving station. This is useful as it allows decisions about the integrity of the data to be made in the application layer (application or the codec), where the significance of the bits is understood.

A datagram is a basic transfer unit associated with a packet-switched network. Datagrams are typically structured in header and payload sections.

In natural and social science research, a protocol is most commonly a predefined procedural method in the design and implementation of an experiment. Protocols are written whenever it is desirable to standardize a laboratory method to ensure successful replication of results by others in the same laboratory or by other laboratories.

<operating system, security> (Or "logon") A unique name for each user of computer services which can be accessed by several persons. Users need to identify themselves for accounting, security, logging, and resource management. Usually a person must also enter a password in order to access a service. Once the user has logged on the operating system will often use a (short) user identifier, e.g. an integer, to refer to them rather than their user name. User names can usually be any short string of alphanumeric characters. Common choices are first name, initials, or some combination of first name, last name, initials and an arbitrary number. User names are often assigned by {system administrators} according to some local policy, or they may be chosen by the users themselves. User names are often also used as mailbox names in electronic mail addresses. (1997-03-16)

A self-contained, independent entity of data carrying sufficient information to be routed from the source to the destination computer without reliance on earlier exchanges between this source and destination computer and the transporting network. See also connectionless, frame, packet.

A power user is a user of computers, software and other electronic devices, who uses advanced features of computer hardware, operating systems, programs, or websites which are not used by the average user. A power user might not have extensive technical knowledge of the systems they use but is rather characterized by competence or desire to make the most intensive use of computer programs or systems.

In international politics, protocol is the etiquette of diplomacy and [of state]. It may also refer to an international agreement that supplements or amends a treaty.