JWT Payload

The payload is the second part of a JWT token and it contains the claims - statements about an entity (usually the user) and additional data. There are three types of claims: 

• Registered - recommended predefined claims that provide a set of useful, interoperable claims. Some of them are: iss (issuer), exp (expiration time), sub (subject), aud (audience) etc. Names are short because a goal of JWTs is for the representation to be compact.
• Public - can be defined at will by those using the JWT
• Private - custom claims created to share information between parties

This JSON is then Base64Url encoded.