advancedJWT: Token-Based Authentication
What are the three parts of a JWT, and what is each one for?
Header (metadata: signing algorithm and token type), Payload (the actual claims — subject, roles, issued-at, expiry, custom data), and Signature (a cryptographic signature over the header+payload proving the token hasn't been tampered with). All three are Base64URL-encoded and separated by dots; only the signature provides integrity, not the encoding itself.
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