TCP vs UDP at a Glance

At the transport layer, two protocols carry most internet traffic: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).

Both move data between applications, but they make very different trade-offs between reliability and speed. Knowing when each is used is core Network+ knowledge.

TCP is connection-oriented: before sending data it establishes a connection, ensuring both sides are ready. It guarantees that data arrives complete and in order.

If a segment is lost, TCP detects the gap and retransmits it. This reliability makes TCP the choice for web pages, email, and file transfers where every byte matters.