JWT (JSON Web Token) is a compact, URL-safe means of representing claims to be transferred between two parties. It is a standardized format used for securely transmitting information, such as user authentication data, between a client and a server. A JWT consists of three parts: a header, a payload, and a signature. The header specifies the token type and signing algorithm, the payload contains the claims (such as user ID and expiration time), and the signature verifies the token's integrity. JWTs are commonly used in authentication and authorization processes to enable secure communication and session management in web applications.