are tiny text files that are stored on your (client)
computer when you login to your account. Cookies are
used to maintain state. In other words, they are
used to make sure that you are you when using your
account. Your cookie is validated again a file save
on our computer (server) to make sure that you are
using the account every time your computer requests
information from the server. You can only be logged
in at one computer at a time, one unique IP address.
For example, say you're using your account at a
friends house and you forget to logout of their
computer. All you have to do to logout from their
computer is login from another computer.