The IAB Europe Transparency and Consent Framework (TCF) is the technical standard for passing user consent across programmatic advertising. Current version: TCF v2.3, mandatory since November 2023. It uses a TC String — a Base64-encoded consent signal sent with every bid request — plus the Global Vendor List (GVL) registering vendors and their declared purposes. Publishers monetising EU/EEA traffic through IAB-integrated ad tech need a TCF-registered CMP. v2.3 tightened rules after the Belgian DPA's 2022 GDPR ruling — disclosed vendors are mandatory, and legitimate interest is no longer allowed for purposes 1-6. TCF signals consent — it doesn't create legal compliance by itself.