Saving and Using Cookies
A cookie is a name-value pair stored within the client browser. Every subsequent request from the client includes all of the previous cookie values.
Storing information within a cookie is useful for information that you want to remember past the end of a session. (To do this, you must set an expiration date as, by default, cookies end when the browser closes.) For example, you could remember a username in a cookie so that in a subsequent session they would not have to reenter this information.