Transmission Control Protocol
Every HTTP request your app makes rides on TCP. Understanding TCP helps with latency, timeouts, keep-alives, and connection pooling.
What It Defines
Defines reliable, ordered, connection-oriented byte-stream transport over IP. The foundation for HTTP/1.1, HTTP/2, SMTP, IMAP, and most internet application protocols.
The canonical publication point for finalized RFCs. If a protocol is standardized as an RFC, the RFC Editor text is the normative final reference. Published by the IETF, IRTF, IAB, and independent stream.
Related Specs
DNS runs over UDP. QUIC and HTTP/3 run over UDP. Media and gaming often use UDP for low-latency delivery.
HTTP/3 runs on QUIC. Modern CDNs and browsers use it by default. It fixes TCP's head-of-line blocking problem for multiplexed requests.
Every HTTPS connection, SMTP/IMAP over TLS, OAuth token exchange, and API call uses TLS. It is the foundational security layer.