A method determines a user demographic profile of an anonymous user that
visits one or more websites of a predetermined group of websites. The
method includes determining whether an anonymous user's computer has user
identification data installed thereon. Determining whether the user
identification data is installed is performed upon the anonymous user
visiting a website of the predetermined group of websites. The user
identification data is unique to the anonymous user. The method further
includes installing the user identification data on the anonymous user's
computer if the anonymous user's computer does not have the user
identification data installed thereon. The method further includes
generating a first record of visits by the anonymous user to the websites
of the predetermined group of websites. The method further includes
providing one or more website profiles comprising demographic
characteristics of each website visited by the anonymous user of the
predetermined group of websites. The method further includes calculating
an estimated user demographic profile of the anonymous user by using the
first record of visits by the anonymous user and the one or more website
profiles.