15.6.4 TCP And UDP Compared

Although both TCP and UDP operate at the Transport Layer, they have been designed for different purposes.

Feature	TCP	UDP
Connection	Connection-oriented	Connectionless
Reliability	Guaranteed delivery	Best effort
Packet Ordering	Preserved	Not guaranteed
Retransmission	Yes	No
Protocol Overhead	Higher	Lower
Typical Applications	Web, email, file transfer	Voice, video, gaming, DNS

Neither protocol is universally better. The appropriate choice depends upon the requirements of the application. Applications requiring reliable delivery generally use TCP, while delay-sensitive applications often favour UDP.