Its name highlights Transmission Control Protocol and Internet Protocol, but the suite includes many other protocols for link access, addressing, routing, transport, naming, configuration, diagnostics, and application communication.
The architecture is commonly described with link, internet, transport, and application layers, although diagrams vary. IP provides addressed, best-effort packet delivery across interconnected networks. TCP provides a reliable, ordered byte stream between endpoints, while UDP provides connectionless datagrams; applications select transports according to need.
Key points
Layered designEach layer offers services to the layer above and uses the layer below, allowing technologies to change independently.
Internet layerIPv4 and IPv6 addressing and routing move packets between networks; ICMP supplies related control and error information.
End-to-end protocolsTransport and application protocols define communication behavior beyond basic packet forwarding, with reliability, ordering, naming, and security handled according to protocol and application requirements.
Important limitationTCP/IP is not a security architecture, and neither a TCP connection nor an IP address proves a user, device, or service is trustworthy. Confidentiality, peer authentication, authorization, integrity, and abuse resistance require suitable protections at one or more layers.