Cookies
When you "log in" to this website (as with all websites), a purely-random "cookie" is used to maintain your session information on the server for the duration. This cookie and the associated session information is discarded when you "log out," or after a few minutes of inactivity, as it is no longer needed.
This is a purely technical consideration common to all such web sites: you must accept this cookie. Cookies are never used to invade your privacy, nor to "track" you, nor to "retain" any information at all about you. (If you do not "log in," no cookies are used.)