First-party data is information a brand collects directly from its own customers and prospects, such as transactions, website activity, CRM data, and owned-channel engagement. Third-party data comes from an external provider and helps extend what a brand knows by adding scale, broader market visibility, and predictive insight. The most effective strategies use first-party data as the foundation and third-party data to enrich, validate, segment, model, and expand that foundation. Alliant is especially useful in that role because its data can help brands connect their own customer truth with broader purchase behavior and psychology-driven insight.