A consent string is a compact, encoded data string generated by a consent management platform that records a user's consent choices — which vendors they have accepted, which data processing purposes they have agreed to, and which they have rejected. Consent strings are a core component of the IAB Transparency and Consent Framework (TCF) and are passed to ad tech vendors in real time so they know whether they are permitted to process a user's data. The string is stored in the user's browser and shared across the programmatic advertising supply chain. Consent strings must be updated whenever the user changes their preferences.