1. A computer implemented method for universal synchronization of profiles of client computers targeted for the delivery of content over a computer network, the method comprising: receiving profile data for a plurality of client computers over the computer network from audience member information collection domains, the profile data including a set of profile data that corresponds to a profiled client computer; maintaining an association between the set of profile data and the profiled client computer in a computer database using a global profile identifier; associating in the computer database the global profile identifier with a set of cookie related information; facilitating the collection of profile data for the profiled client computer using the set of cookie related information; collecting at the computer database profile data for the profiled client computer as a result of activity in one of the audience member information collection domains by the profiled client computer; receiving over the computer network an authoritative identification of the profiled client computer as a result of activity by the profiled client computer in one of the audience member information collection domains; using the authoritative identification to correlate the profiled client computer to the global profile identifier; receiving over the computer network a set of cookie related information from the profiled client computer; determining that the set of cookie related information received from the profiled client computer does not include at least part of the set of cookie related information associated with the global profile identifier; and restoring on the profiled client computer cookie related information which was determined not to be included in the set of cookie related information received from the profiled client computer.