While similar to first party data in that it is “owned” by the brand, zero party data is information that a customer has intentionally provided, rather than (in the case of first party data) collected by a brand based on a customer’s behavior.
Forrester defines it as such:
“Data that a customer intentionally and voluntarily shares with a brand, usually in exchange for a benefit, such as an exclusive offer or reward. It can include preference center data, purchase intentions, personal context, and how the individual wants the brand to recognize them.”
Zero party data can include information submitted in forms, survey answers, and other information, and individual customers explicitly provide this information to brands through these means.
Zero party is often demographic, though specifically communicating intent could be considered behavioral. This area in particular is one where brands need to concern themselves with the storage of Personally Identifiable Information (PII), as well as to ensure they are in compliance with regulations such as the Health Insurance Portability and Accountability Act of 1996 (otherwise known as HIPAA).
 Forrester. “The Data Deprecation Challenge and the Promise of Zero-Party Data.” 2022.