Cookie

Meaning

A cookie is a small piece of data stored by the browser and sent back to the server with later requests to the same site. Sites use cookies to carry a session identifier, remember a preference or recognise a returning visitor. Because the browser attaches cookies automatically, they are also the reason request forgery attacks are possible, so security attributes such as secure, HttpOnly and SameSite matter. Never store passwords or sensitive details directly in a cookie. See also: Session, CSRF, and the guide How PHP Works on the Server: Request and Response Explained.