Glossary/Privacy & Identity/Unified ID 2.0 (UID2)
Privacy & Identity
Unified ID 2.0 (UID2)
An open-source identifier built on hashed, consented email addresses.
By Brandon Mina·CEO, BrandPilot AI·Updated November 2026
Appears in Lesson 6 of Programmatic 101
Short answer
Unified ID 2.0 (UID2) is an open-source advertising identifier built from hashed and encrypted email addresses or phone numbers that users provide with consent. Developed by The Trade Desk and now operated with industry partners, it is designed as an alternative to third-party cookies. UID2 enables addressable targeting and measurement across websites, apps, and CTV.