세션과 무상태 토큰 비교

HTTP forgets you between requests. To keep someone logged in, you either store a session on the server or hand the client a signed token.

With a session, the server keeps your login state and gives the browser a tiny cookie holding only a session id. Every request, the server looks that id up. 🍪

Because the server stores the state, it must remember every active user. That server-side state gets heavy and tricky to share across many machines.

A token carries the user info itself, signed by the server. The server no longer stores anything; it just verifies the signature on each request.

Stateless means the server holds no memory of the client. Everything it needs to trust you travels inside the token on each call.

A JWT (JSON Web Token) is the standard stateless token. It is a compact, signed string that any server with the key can verify instantly.

A JWT has three dot-separated parts: a header, a payload, and a signature. The header names the algorithm used to sign it.

The middle part holds claims: small facts like the user id or an expiry time. It is encoded, not encrypted, so never put secrets there.

The signature is made from the header, payload, and a secret only the server knows. Change one byte and verification fails.

Tokens shine for APIs and mobile clients that scale across many servers, since no shared session store is needed to verify a caller.

For a classic server-rendered website, sessions are simpler and easy to revoke. The right pick depends on your app, not on hype.

Think about what makes a token approach stateless.

Sessions store state on the server; JWTs push signed state to the client. Tokens stay stateless, making them a great fit for scalable APIs. 🚀