The User Datagram Protocol
The User Datagram Protocol, commonly known as UDP, is a core member of the Internet Protocol Suite. Originally defined by David P. Reed in 1980, the protocol is formally specified in RFC 768. Unlike the Transmission Control Protocol (TCP), UDP is a connectionless protocol, meaning it does not establish a dedicated end-to-end connection before data transfer begins.
Because UDP does not provide error correction, flow control, or packet sequencing, it is often referred to as an unreliable protocol. However, these omissions result in significantly lower latency and overhead. This makes it the preferred choice for real-time applications such as Voice over IP (VoIP), Online Gaming, and Live Streaming. It is also used for simple query-response protocols like Domain Name System (DNS) and the Dynamic Host Configuration Protocol (DHCP).
The UDP Header consists of only four fields: the Source Port, the Destination Port, the Length, and the Checksum. This 8-byte header is much smaller than the 20-byte header typically used by TCP, allowing for more efficient use of Bandwidth at the Transport Layer of the OSI Model.