Question: What is the usage of UDP (User Datagram Protocol)?

UDP (User Datagram Protocol) is connectionless Transport layer protocol. Connectionless means it does not require connection establishment and provide reliability as TCP does, so the packets might be lost after sending.

The UDP packet is just sent without tracking and no acknowledgement when it’s received, so it’s more like normal postal mailing service; you send a mail to friend, after that you might not aware that whether your friend has received it or the mail is lost somewhere. The benefit of UDP, it is faster than TCP due to less checking during the sending process.

UDP is usually used in video/audio streaming, online game and other applications that the connection reliability is not so important.