Cookies-The authenticator

Cookies are the encrypted text file used for the authentication of a particular person.It is produced by the web server and consumed by web server.For example you cant login to your email account when the cookies are blocked in your browser and it will prompt you to turn on the cookies.This is because when you login from a particular browser in a system it will send a cookie for identification of a particular person and it will be required for every action such as opening of email.Cookies can also be a spyware but some websites are unusable without cookies.As cookies contain sensible information every cookie has am expiration time as decided by the web server.