What are internet cookies?
Internet cookies are small pieces of data that a browser stores in relation to a site and can attach to eligible requests. They can support sessions, language preferences and shopping carts. A cookie is not a program and cannot execute code on a device by itself.
How cookies are used
A server can create a cookie with the Set-Cookie header; the browser adds a Cookie header to later requests when scope and rules permit. Session cookies and persistent cookies with expiration times have different lifecycles. Domain and path settings affect their scope. The Secure attribute restricts transmission to secure connections; HttpOnly blocks JavaScript access and reduces some attack impacts. SameSite affects transmission with cross-site requests. These attributes do not solve every security problem. Session identifiers must be unpredictable, validated on the server and governed by logout and expiration rules.
Privacy and user experience
First-party and third-party cookies differ by context, and browser policies may restrict third-party use. A cookie's technical classification alone does not determine whether it is necessary or insignificant for privacy. Its purpose and stored data matter. Clearing cookies can sign users out or reset preferences, but should not be assumed to eliminate all online tracking. Other mechanisms, including local storage, also exist. Developers should avoid placing unnecessary personal information in cookies, explain their purposes clearly and provide preference management consistent with applicable law. Remembering a language choice and profiling behavior across different websites are not equivalent activities.