User Datagram Protocol (UDP)

UDP is also a core member of the internet protocol suite. Like TCP, it is on layer 4 of the OSI model that is responsible for delivering data segments between the application and the IP layer. Unlike TCP, their header is only 32-bit that only consists of source and destination port, length, and checksum. The lightweight header makes it ideal for the application to prefer a faster data delivery without setting up the session between two hosts or needing a reliable delivery of data. Perhaps it is hard to imagine in today's fast internet connections, but the extra header made a big difference in the speed of transmission in the early days of X.21 and frame relay links. Although as important as the speed save, not having to maintain various states such as TCP also saves compute resources on the two endpoints.

You might now wonder why UDP was ever used at all in the modern age; given the lack of reliable transmission, wouldn't we want all the connections to be reliable and error free? If one thinks about some of the multimedia video streaming or Skype call, those applications will benefit from a lighter header when the application just wants to deliver the datagram as fast as possible. You can also consider the DNS lookup process. When the address you type in on the browser is translated into a computer understandable address, the user will benefit from the lightweight process since this has to happen "before" even the first bit of information is delivered to you from your favorite website.

Again, this section does not do justice to the topic of UDP, and the reader is encouraged to explore the topic through various resources if he/she is interested in learning more about UDP.