UDP, or User Datagram Protocol, is a communication protocol used for sending data over a network. It is part of the Internet Protocol suite and operates on top of IP. Unlike TCP (Transmission Control Protocol), UDP does not establish a connection before sending data, which makes it faster but less reliable. It is often used for applications where speed is more critical than accuracy, such as online gaming, video streaming, and voice calls. UDP sends data in small packets called datagrams. Each datagram is sent independently, and there is no guarantee that they will arrive in order or even reach their destination. This means that applications using UDP must handle any lost or out-of-order packets themselves. Despite its limitations, UDP is favored for real-time applications due to its low latency and reduced overhead.