protocols

Protocol is a formal set of rules and conventions that govern how entities communicate to achieve a shared goal. A protocol defines the structure of messages (syntax), the meaning of those messages (semantics), and the timing or ordering of interactions. By standardizing these elements, protocols enable interoperability among heterogeneous systems and predictable behavior under varying conditions.

Protocols are used across many domains, including computing, networking, diplomacy, and biology. In information technology, protocols are often organized into layers, from physical signaling to application-level services. Examples include TCP for reliable transport, IP for addressing and routing, HTTP and HTTPS for web communication, SMTP for email, and TLS for security. Protocols may be connection-oriented or connectionless, and may employ handshakes, state machines, error detection, and flow control. They specify how sessions are established, how data is formatted and transmitted, and how disputes or errors are resolved.

Standardization and governance are carried out by organizations such as the Internet Engineering Task Force (IETF), ISO, IEEE, ITU, and W3C. Specifications may be published as RFCs or international standards. Implementations must adhere to the protocol to ensure interoperability; deviations can cause failures and security risks. Protocols also address security and privacy through authentication, encryption, integrity checks, and access control. As technologies evolve, protocols are revised and extended, with versioning and feature negotiation to maintain compatibility while enabling new functionality.