The cookie itself is a file stored on the client and read by the server during each on-line session. For example, at a travel Web site, a cookie may tell the server that the user who is booking a flight to San Jose likes to sit on the aisle and eat vegetarian meals. No doubt, cookies can be a handy feature. But they can do more than store preferences. An on-line newspaper or magazine could track and record particular articles a user has accessed, creating a log of his or her activity.
Sites have other ways to collect information as well.
In a registration process, a valid E-mail address may be required in order to receive a password to use the site. An on-line form may ask about hobbies and interests. Most users are unaware of the amount of information they unwittingly send Web sites. A blank E-mail, for example, sent in order to receive a password, will often contain the user's real name and place of employment. These are fields most users have entered into their E-mail software without a second thought.