What does TCP stand for?
TCP stands for Transmission Control Protocol. Transmission Control Protocol: connection-oriented transport using the SYN, SYN-ACK, ACK handshake. Flags and ports in TCP traffic are key evidence in network analysis.
TCP is the transport protocol used when data must arrive complete and in order. Before any data is sent, the two ends open a connection with a three-way handshake: SYN, SYN-ACK, ACK. Every segment is numbered and acknowledged, lost segments are sent again, and the sender slows down when the receiver or the network cannot keep up. Web pages, email, file transfers and remote shells run over TCP. Each connection is identified by the two IP addresses and the two port numbers, which is also what a NAT device tracks.
TCP in practice: an example
A user downloads a 2 GB installer over hotel Wi-Fi that drops packets. The download is slower than usual but the file is intact, because TCP noticed each missing segment and requested it again. The application did nothing; reliability was handled by the transport layer.
What TCP is confused with
TCP vs UDP: what is the difference?
TCP sets up a connection and guarantees ordered delivery, at the cost of overhead and delay. UDP sends independent datagrams with no guarantee, which suits live voice, video and short queries. What UDP stands for
Which exams cover TCP?
TCP is on the official CompTIA acronym list for three of the four exams covered here.
- CySA+ CS0-004: on the acronym list, not tied to one objective.
- Network+ N10-009: 1.0 (Networking Concepts).
- A+ 220-1201 and 220-1202: 220-1201 2.0 (Networking).
Each number is a CompTIA exam objective and the name in brackets is its domain. The exam puts the term in a scenario; it does not ask you to recite the expansion.
Check yourself: two practice questions
Written by CertSprint for this page. They are not taken from any exam.
1. What is the correct order of the TCP three-way handshake?
- SYN, SYN-ACK, ACK
- ACK, SYN, FIN
- SYN, FIN, ACK
- SYN-ACK, SYN, ACK
Show the answer
A. SYN, SYN-ACK, ACK. The client sends SYN, the server answers SYN-ACK and the client completes the handshake with ACK.
2. An application must transfer a database backup without any missing or reordered bytes. Which transport protocol fits?
- UDP
- TCP
- ICMP
- ARP
Show the answer
B. TCP. TCP numbers, acknowledges and retransmits data, so the receiver gets every byte in order. UDP offers no such guarantee.
Sources: RFC 9293: Transmission Control Protocol (TCP); RFC 1122: Requirements for Internet Hosts, Communication Layers. The acronym and its expansion come from CompTIA's official acronym lists, linked from each exam glossary above. The explanation, example and questions are CertSprint's own, checked against these sources on 11 November 2026.