In the case of communication with UDP, the client does not establish a connection with the server but simply sends a datagram. The server does not have to accept a connection; it simply waits for datagrams to be sent from the client. Every datagram contains the address of the sender, enabling the server to identify the client on the basis of where the datagram is sent from.
For communication, the UDP server first creates a UDP socket and binds it to the server address. Then, the server waits until the datagram packet arrives from the client. Once it has arrived, the server processes the datagram packet and sends a reply to the client. This procedure keeps on repeating.
On the other hand, the UDP client, for communication, creates a UDP socket, sends a message to the server, and waits for the server's response. The client will keep repeating the procedure if they want to send more messages to the server, otherwise the socket descriptor will close.