JWT

JSON Web Token (JWT) is an open standard (RFC 7519) that defines a compact and self-contained way for securely transmitting information between parties as a JSON object. This information can be verified and trusted, as it is digitally signed. JWTs are often used for authentication and authorization purposes in web development.

A JWT is composed of three parts:

1. Header: The header typically consists of two parts: the type of the token, which is JWT, and the signing algorithm being used, such as HMAC SHA256 or RSA. 
2. Payload: The payload contains the claims. Claims are statements about an entity (typically, the user) and additional data. 
3. Signature: To create the signature part, you have to take the encoded header, encoded payload, a secret, and the algorithm specified in the header, and sign that.   

JWTs are widely used for authentication and authorization because they are stateless, meaning the server doesn’t need to store the user’s information or session data. Once a user is authenticated, the server can issue a JWT containing information about the user, and the client can include this token in subsequent requests to access protected resources. The server can then verify the token’s signature to ensure its integrity and authenticity.

It’s important to use secure communication channels (e.g., HTTPS) to prevent man-in-the-middle attacks, and to store sensitive information or use appropriate encryption mechanisms if needed. Additionally, JWTs have an expiration time, reducing the risk associated with long-lived tokens.