Why are they called cookies?
Good question... no one really knows.
A cookie was originally designed to store small amounts of information in your web browser which was sent back to a server to provide information such as your username or login ID; this helped to make things more convenient. Think of a cookie as a token or ticket.
But, how did cookies get that name? The answer isn't exactly known other than it might be related to what was organically called a "magic cookie." Some believe that a cookie goes back to the Hansel and Gretel fairy tale where the siblings used cookie crumbs to mark their trail through the forest. However, if that's the case, then I would have expected them to be called crumbs, not cookies.
My personal theory of choice is that cookie is short for "fortune cookie," in that it contains a small message similar to a fortune cookie.