Sessions and JSON Web Tokens (JWTs) are two ways to carry or maintain authentication state. The right choice depends on architecture, revocation needs, and browser security.

Session flow

• User submits credentials; the server verifies them.
• The server creates a session in server-side storage.
• The client receives a session ID, commonly in a cookie.
• The client sends the cookie with later requests; the server looks up the session.

JWT flow

• Server verifies credentials and issues a token.
• A typical JWT has a header, payload, and signature.
• The client sends the token according to the application's security design.
• The server validates signature and relevant claims such as issuer, audience, and expiration.

Comparison

• Sessions: state is usually server-side; central invalidation is often straightforward; shared session storage may be needed across instances.
• JWTs: claims travel in the token; validation can reduce session lookups in suitable designs; immediate revocation requires additional design.
• A signed JWT is not automatically encrypted; its payload is generally readable by anyone who has it.

Security practices

• Use HTTPS and short-lived access tokens where appropriate.
• Protect refresh tokens and avoid sensitive secrets in token claims.
• Carefully choose cookie or browser storage strategies.
• Consider CSRF risks with cookies and XSS risks when tokens are accessible to JavaScript.