What is the difference between TCP and UDP?

TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) are two main transport layer protocols in the OSI model, used for data transmission over a network.

Main differences:

• Reliability: TCP ensures reliable data delivery by establishing a connection, confirming receipt of packets, and retransmitting lost packets. UDP does not guarantee delivery; packets may be lost without notification.

• Connection: TCP is connection-oriented, starting with establishing a connection. UDP is connectionless.

• Speed: UDP is faster because it does not spend time on connection setup and acknowledgments.

• Order of delivery: TCP guarantees the order of packet delivery, UDP does not.

• Usage: TCP is suitable for applications where reliability is important (web, email, file sharing). UDP is used for applications where speed is crucial and some loss is acceptable (streaming, online gaming, VoIP).

Example:

TCP: the client establishes a connection with the server, sends a request, receives an acknowledgment and response.
UDP: the client simply sends a datagram to the server without acknowledgment.