A session token is a unique identifier used to manage a user's session on a website or application. When a user logs in, the server generates this token and sends it to the user's device. The token helps the server recognize the user in subsequent requests, allowing for a seamless experience without needing to log in repeatedly. Session tokens enhance security by limiting the duration of a session. If a user remains inactive for a certain period, the token expires, requiring the user to log in again. This helps protect sensitive information and ensures that only authorized users can access their accounts during an active session.