UDP (User Datagram Protocol) is a connectionless network protocol used for transmitting data with minimal overhead. Unlike TCP, UDP does not establish a connection before sending data, nor does it guarantee delivery, order, or error checking. This makes UDP faster and suitable for applications where speed is more important than reliability, such as online gaming, live broadcasts, and DNS lookups. However, its lack of built-in reliability means developers must handle lost or out-of-order packets themselves. UDP is less commonly used in web browsers today due to security and compatibility concerns, but it remains vital in many real-time communication systems.