Stateless

Stateless describes systems or processes that do not rely on stored state between requests or interactions. In computing, a stateless system processes each request independently, without relying on stored context. This contrasts with stateful systems that preserve information about previous interactions.

In network protocols, HTTP is stateless by design; each request is independent. Servers may track state through client-provided context such as cookies, tokens, or server-side sessions, but the core protocol remains stateless.

In software architecture, stateless services, microservices, and RESTful APIs favor statelessness for scalability and reliability. Session data can be stored on the client or in a distributed store, with tokens or opaque session IDs used to authenticate and authorize.

Advantages include improved scalability, easier load balancing, and simpler recovery after failures. Disadvantages include the need to reauthenticate frequently, managing user context across requests, and potential overhead from token validation or token refresh.

Statelessness also refers to individuals who are not considered nationals by any state. This can result from gaps in nationality laws, displacement, or loss of citizenship, and may entail limited access to civil rights and services.

Related concepts include stateless protocols, token-based authentication, and stateless design patterns in software engineering.