Stateless
A stateless protocol treats every request as independent – no information from previous requests is retained on the server. HTTP is stateless by design. Each request must contain all information needed to process it. Cookies, sessions, and JWTs are mechanisms layered on top of HTTP to simulate statefulness.
Definition
Statelessness means the server retains no memory of past interactions. HTTP/1.1 is stateless: each request stands alone. This enables horizontal scaling – any server in a pool can handle any request because no server-side state is needed. The trade-off: each request must carry its own authentication, session, and context. Cookies and Authorization headers are how clients re-present state on each request. Sessions store state server-side but require sticky sessions or shared storage (Redis). JWTs embed state in the token itself so no server-side storage is needed.