This website uses a transient cookie, sometimes called a session cookie, which is a small file that contains information about a user that disappears when the user's browser is closed. Unlike a persistent cookie, a transient cookie is not stored on our hard drive, but is only stored in temporary memory, that is erased when the browser is closed.
A transient cookie is created by simply not setting a date in the Set-Cookie option when an application creates the cookie (for a persistent cookie, an expiration date is set and the cookie is stored on the user's hard drive until the expiration date or until the user deletes it.)
Transient cookies are often used to enable a site to be able to track the pages that a user has viewed during a visit, so that information can be customized for the user in some way. Some sites use Secure Sockets Layer (SSL) to encrypt the information contained in a cookie.