Authentication is the process of verifying the identity of a user or client. It ensures that only authenticated users have access to protected resources. On the other hand, authorization is the process of determining what a user can and cannot do on a system or application. It specifies the permissions and privileges of users to access different resources. 

Tokens and sessions are two common methods of implementing authentication in REST APIs. Tokens are secure, unique strings generated by the server that are used to authenticate a user for a specific period. In contrast, sessions are server-side storage of user data that are stored as cookies in the user's browser. 

Role-based access control (RBAC) is a common method of implementing authorization in REST APIs. In this method, users are assigned roles based on their job functions or responsibilities. Each role is associated with a set of permissions, which specify the operations that the user can perform.

Overall, authentication and authorization are vital components of building secure and trustworthy REST APIs. By implementing them correctly, we can ensure that only authenticated and authorized users have access to the resources they need while maintaining the security and integrity of the system.

JWT stands for JSON Web Token, which is a compact, URL-safe means of representing claims to be transferred between two parties. It is used for authentication and authorization purposes in web applications and RESTful APIs.

A JWT consists of three parts: a header, a payload, and a signature. The header contains information about the type of token and the algorithm used to sign it, the payload contains the claims or information about the user, and the signature is used to verify the authenticity of the token.

JWTs are often used to implement stateless authentication in web applications, where the user’s state is not stored on the server. When a user logs in, they are issued a JWT, which is then sent with each subsequent request to authenticate the user.

One advantage of using JWTs is that they can be verified on the client-side, which reduces the load on the server. JWTs can also be used to exchange information between services, since they can be signed and verified by different parties.

Overall, JWTs provide a secure, efficient, and easy-to-use solution for implementing authentication and authorization in web applications and RESTful APIs.