In general, systems, components, methods, and techniques for gathering, recording, and development of accurate user demographics attributed to accesses by client systems of webpage, web content, or other online resources is provided. For a given a subset of unique users having known demographics for a segment of traffic or general population, a demographic profile may be created for all users of the segment or population within a tolerable margin of error. Demographic data for unique machine identifications (IDs) may be assigned, aggregated, and derived from a single source, or multiple sources, such as panel data, beacon level surveys, cookie exchanges, and the overlay of profile cookies from other publishers.