Third-party data differs from both first- and second-party data in that it comes from an outside source indirectly. Third-party organizations may not have direct links to the audience the data comes from but will collect data from multiple platforms and organize it into sets for purchase. Third-party data can be unreliable by itself and, historically, has been used by marketers to identify segments of prospective customers. For example, a mortgage company could purchase Third-party data representing people who recently spent time looking at houses on a real estate website. The Third-party data generally does not provide an individual’s name, address, or any other personally identifiable information (PII), but does provide marketers with enough insight on where to utilize advertising resources.
Like Second-Party data, Third-Party data is under increased scrutiny and regulation by privacy rules, and additionally may rely on technologies (like third-party cookies) that are being deprecated or blocked by some technology providers.