A persistent cookie, also known as a stored cookie, is a file that is stored on a user’s hard drive. The cookie would remain on the hard drive until it reaches its expiration date. At this point the browser would purge the cookie from the hard drive. On every subsequent visit to the website the browser will send the cookie back to the web site. Because a cookie’s value can uniquely identify a client, the cookie can indicate how the user initially came to this website. For this reason, they are also sometimes referred to as tracking cookies.