CyberGuard dictionary / Network Security
Transmission Control Protocol
Transmission Control Protocol is a connection-oriented transport protocol that provides an ordered, reliable byte stream between applications.
In simple terms
TCP tracks a conversation and handles lost or out-of-order segments so applications can read a continuous stream.
Technical explanation
TCP uses sequence and acknowledgment numbers, retransmission, flow control, and congestion control. It does not encrypt content by itself; applications commonly add TLS when confidentiality and peer authentication are needed.
TCP establishes a connection, numbers data, acknowledges delivery, and retransmits missing segments. These features support reliable byte streams but do not provide encryption or application authentication.
Examples in practice
A browser opens a TCP connection to a web server, then uses TLS and HTTP over that connection to load a page.
A file transfer continues correctly after a few packets are lost because TCP retransmits them. The application still uses TLS to protect the file contents in transit.
Why it matters
Knowing what TCP provides helps distinguish transport reliability from application security and encryption.
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Sources and further reading
Published 2026-10-15 · Last updated 2026-10-15 · CyberGuard editorial content. Source links provide context; they do not imply endorsement.