What Is TCP?
TCP — the Transmission Control Protocol — the reliable, connection-oriented transport protocol that guarantees data arrives complete and in order, underpinning most internet traffic.
How it works
TCP establishes a connection with a three-way handshake (SYN, SYN-ACK, ACK), then numbers every segment and acknowledges receipt. Lost segments are detected (missing acknowledgments) and retransmitted; segments are reassembled in order. This reliability makes TCP ideal for web pages, email and file transfers — anything that must arrive perfectly.
Why it matters
TCP carries the majority of internet traffic and is fundamental to networking — the handshake and reliability mechanisms are guaranteed exam and interview topics. Its trade-off (reliability at the cost of overhead) is why UDP exists for speed-critical uses.
Frequently asked questions
What is TCP?
The Transmission Control Protocol — a reliable, connection-oriented transport protocol that guarantees data arrives complete and in order using acknowledgments and retransmission.
What is the TCP three-way handshake?
The connection setup: client sends SYN, server replies SYN-ACK, client sends ACK — then data transfer begins.
When is TCP used instead of UDP?
When reliability matters more than speed — web pages, email, file transfers — where every byte must arrive correctly and in order.
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