HTTP/1.1: The original language of the web — one request at a time, in plain text.
HTTP/2: Multiplexed, binary HTTP — many requests flying over one connection simultaneously.
HTTP/3: HTTP over QUIC — faster connections, no head-of-line blocking, built-in encryption.
WS: Full-duplex, persistent connection — server and client talk freely in real time.
gRPC: High-performance RPC framework using Protocol Buffers over HTTP/2.
GraphQL: Ask for exactly the data you need — no more, no less. A query language for APIs.
SSE: One-way real-time streaming from server to browser over plain HTTP.
REST: An architectural style for web APIs — not a protocol, but the dominant pattern for HTTP services.
MCP: A universal interface that lets AI applications discover and use tools, data, and prompts from any server.
A2A: An open protocol that lets AI agents discover each other, delegate tasks, and collaborate — even across different frameworks and vendors.
JSON-RPC: A minimal RPC protocol encoded in JSON — call a method by name, get a result back. Nothing more.
SOAP: XML-based messaging for enterprise web services — structured envelopes, strict schemas, and built-in error handling.