Third-party data refers to data that is collected and owned by a third-party company or organization, rather than by the individual or entity that is using the data. In the context of advertising and marketing, third-party data is typically data that is collected by a data provider or marketing technology company, and that is then sold or licensed to advertisers or publishers for use in targeting and measuring their advertising campaigns. Third-party data can include a wide range of information, such as demographic data, behavioral data, or geographic data, and can be used to target ads to specific groups of users, based on their interests, behaviors, or location. Third-party data can be an effective way for advertisers and publishers to improve the relevance and performance of their advertising, but it can also raise concerns about privacy and the potential for users to be tracked and targeted without their knowledge or consent.