Third-party data
Third-party data is collected by a company with no direct relationship with the people it describes, and sold or licensed to advertisers to target their campaigns.
For more than a decade it was the backbone of programmatic targeting. Specialist providers collected the browsing of millions of users through cookies and pixels placed on thousands of sites, grouped it into categories (travel intenders, car enthusiasts, parents-to-be) and offered it in DMPs and DSPs. Its strength was scale: a segment of millions of people could be bought in a few clicks.
Its weakness is provenance. It is rarely clear how someone was judged to be interested in something, or whether they gave valid consent. With Safari and Firefox blocking cookies, the GDPR and advertisers’ growing mistrust, the market has shrunk: Oracle, one of its biggest names, stopped selling it in Europe in 2020 because of the GDPR and in 2024 announced the closure of its entire advertising business. The preference now is for data with a clear origin, whether a company’s own, a partner’s or based on verifiable behaviour.
