Session Management Security

Session management is how applications maintain user state after authentication. A user logs in, the server creates a session (storing their ID and permissions), and the client uses a session ID (in a cookie or token) to prove they're that user. Session management security ensures only the legitimate user can use their session, sessions expire, stolen sessions are detected/revoked, and attackers can't trick users into unknowingly making requests (CSRF). Modern approaches split into two: server-side sessions (store all data on the server) and tokens (store data in the token itself, signed by the server). Both have trade-offs.