1. A method for tracking activity on a web site comprising: storing a web site on a first server coupled to a network, said website belonging to a first-party domain; using a second server at a second domain, different from the first-party domain, to place a third-party cookie on a visitor computer to track activity of the visitor computer on the first server; loading a web page from the web site on the visitor computer; executing computer code associated with the web page at the visitor computer; sending a data request to the second server responsive to execution of the computer code; generating identification code at the second server responsive to the data request and returning the identification code from the second server to the visitor computer; and associating at the visitor computer the identification code with a first-party cookie, said first party cookie being associated with the first-party domain; again loading a web page from the web site on the visitor computer; storing information about the visit to the web site in the first-party cookie; opening the first-party cookie at the visitor computer; and sending the information about the web visit to the second server.