Reference / Glossary / Privacy and regulation
Personal Data
Also: Personally identifiable information; PII
Information relating to an identified or identifiable person. Under the GDPR the definition includes cookie IDs, device IDs, IP addresses, and hashed emails; US law historically used the narrower personally identifiable information, but state privacy laws have converged on the broad definition. Most advertising identifiers are personal data.
Related terms
Cite this entry:
Agency Echelon. "Personal Data." Agency Echelon Reference, reviewed September 2026. https://agencyechelon.com/reference/glossary/personal-data/