User Datagram Protocol
UDP applications use datagram sockets to establish host-to-host communications. Sockets bind the application to service ports that functions as the endpoints of data transmission. A port is a software structure that is identified by the port number, a 16 bit integer value, allowing for port numbers between 0 and 65,535. Port 0 is reserved, but is able to be used if the sending process does not expect messages in response.