Second-party data is obtained through partnerships with other entities, and is basically their first-party data. To illustrate, a price comparison site might share their first-party customer data with an e-commerce site. To the e-commerce site, this is second-party data – and is indeed very valuable. Often, partners would mutually share their first-party data in order to gain a better user understanding, or to extend their cross-device ID recognition. Second-party data sharing can also take the form of data co-ops, where multiple partners (typically publishers) pool their data together.
