The article discusses the JSON Web Token (JWT), a self-contained authentication token used for secure communication between server and client. JWT consists of three parts: Header, Payload, and Signature.
The header contains information about the token type and the hashing algorithm used for creating the signature. The payload contains user-specific information, such as issuer, subject, and expiration time, in a JSON object format. The signature is a key or token created by taking the header and payload and appending it with the secret key, which is then hashed using the hashing algorithm provided in the header.