User Datagram Protocol (UDP)
User Datagram Protocol (UDP) is a communication protocol with limited error checking, in the form of a simple checksum. This can be disabled if speed is important. The UDP datagram includes a pseudoheader containing the destination address, facilitating misdirected datagram checking. If the receiving machine finds a datagram directed to an inactive or undefined port, it returns an Internet Control Message Protocol (ICMP) message notifying the source that the specified address is unreachable. There is no resequencing in UDP. On a large network segments of data can take many different routes to a single address, hence requiring resequencing at the address. Because UDP does not provide this, multi-segmented packages of data can become corrupted in transit.