Data & identity · also called Clean room, DCR
Data clean room
A data clean room is a secure environment where companies combine and analyse their customer data together, getting aggregated insights or audiences without exposing each other's raw personal data.
Brands, retailers, publishers and platforms each hold valuable customer data, but sharing raw lists is risky and often unlawful. A clean room lets them match and analyse data together under strict rules: only approved queries run, outputs are aggregated above minimum thresholds, and no party can see the other's individual records.
Common uses include measuring whether people exposed to a campaign bought a product, finding audience overlaps for targeting, planning reach across publishers, and powering retail media and closed-loop measurement. Walled gardens offer their own clean rooms, such as Google Ads Data Hub and Amazon Marketing Cloud, and neutral providers built on cloud data platforms serve many parties. IAB Tech Lab has published interoperability standards so clean rooms can work together.
Clean rooms are privacy-enhancing, not a legal exemption. The data inside is still personal, so consent and lawful basis under laws like GDPR and DPDP still matter, and weak query controls can leak information. Matching usually relies on hashed emails or IDs like RampID.
Think of it like this
A clean room is like two chefs each bringing secret ingredients to a sealed kitchen where only the finished dish, not the recipes, comes out.
An example
A cereal brand and a UK supermarket match data in a clean room and learn that households exposed to the brand's video ads bought 9% more cereal than similar unexposed households, without either side seeing the other's customer list.
Related terms
First-party data
First-party data is information a company collects directly from its own customers or audience, such as purchases, sign-ups, app use and site behaviour, through its own channels.
Second-party data
Second-party data is another company's first-party data shared directly with you through a partnership, such as an airline sharing audience insights with a hotel chain.
Closed-loop measurement
Closed-loop measurement links ad exposure directly to actual sales data for the same people, typically within a retailer or data owner, showing whether ads led to purchases.
Hashed email
A hashed email is an email address transformed by a one-way cryptographic function, usually SHA-256, into a fixed string used to match users across systems without sharing the plain address.
Retail media
Retail media is advertising sold by retailers, on their own websites, apps and stores or elsewhere using their shopper data, letting brands reach customers close to the point of purchase.
Sources: IAB Tech Lab Open Private Join & Activation (clean rooms), GDPR Article 5: principles