Stateless architecture is a system design where each request includes all of the context needed to process it independently. The server does not rely on hidden session state from earlier exchanges, so any instance can handle any valid request. This makes systems easier to scale, restart, and route through load balancers or gateways.
In cyber security, statelessness changes how trust is enforced. Because the server cannot assume prior context, authentication, authorization, and request integrity must be checked on every call, often using signed tokens, identity assertions, and explicit routing metadata. This reduces some risks tied to fragile server-side sessions, but it can also create new ones if context is incomplete, replayable, or validated differently across services. In real defenses, stateless design supports cloud-native resilience; in real attacks, it can be abused when an attacker forges request context, replays valid requests, or exploits inconsistent policy handling between components.