What is Session?
A session is server-side state tied to a particular user's visit, usually identified by a session ID stored in a cookie. Unlike a JWT, a plain session requires the server to look up that state (often in memory or a database) on every request, which is simpler to revoke but harder to scale across multiple servers without a shared store.
Example
Logging a user out server-side usually means deleting their session record, instantly invalidating their session cookie.
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