The User Datagram Protocol (UDP) is a communication protocol used for transporting packets across networks. It is one of the core communication protocols of the Internet protocol suite used to send messages to other hosts on an Internet Protocol network. UDP is a simple message-oriented transport layer protocol that does not require prior communication to set up communication channels or data paths. It uses a simple connectionless communication model with a minimum of protocol mechanisms. UDP provides checksums for data integrity and port numbers for addressing different functions at the source and destination of the datagram. UDP is an alternative to Transmission Control Protocol (TCP), and both UDP and TCP run on top of IP and are sometimes referred to as UDP/IP or TCP/IP. However, there are important differences between the two. For example, UDP enables process-to-process communication, while TCP supports host-to-host communication. UDP is used for time-sensitive applications like gaming, playing videos, or Domain Name System (DNS) lookups. It is also suitable for simple query-response protocols such as the Domain Name System (DNS) and routing update protocols like Routing Information Protocol (RIP). UDP is more efficient in terms of both latency and bandwidth compared to TCP. However, UDP provides no guarantees to the upper layer protocol for message delivery, and the UDP layer retains no state of UDP messages once sent. For this reason, UDP is sometimes referred to as Unreliable Datagram Protocol.