TCP (Transmission Control Protocol) is the backbone of reliable internet communication. It guarantees that data packets arrive in order and without errors — making it essential for web browsing, email, and file transfers.
How TCP Works
TCP establishes a connection using a three-way handshake (SYN, SYN-ACK, ACK) before any data is sent. This ensures both sides are ready to communicate. If a packet is lost in transit, TCP automatically retransmits it.
TCP vs UDP
Unlike UDP, TCP sacrifices some speed for reliability. It is the right choice whenever data integrity matters more than latency — HTTP/HTTPS, FTP, and SMTP all run over TCP.
Learn more about the network protocols that power the internet, or use our port reference to look up common TCP ports.