Some facts:
.).
The first section represents the heading, the second one the payload and the third one the
signature.
alg is the algorithm used to calculate the signature,
typ is the token type (JWT in this case).
Don't put sensitive information in your heading.
iss is the issuer,
aud is the audience,
iat is the issued at timestamp,
exp is the expiration timestamp.
These attributes are also known as claims.
Don't put sensitive information in your payload.