Zero Party Data [0PD or ZPD] is data that your customers give you. From MarTech Alliance: "What is the difference between zero and first party data? Zero-party data is data that your customers intentionally share with you. This can include purchase intentions, personal context, communication preferences, and how the individual wants the brand to recognize them.... On the other hand, first-party data gives you insights from analytics and user behaviors." Compare with First Party Data, Second Party Data, and Third Party Data.
