PPC Land’s explainer unpacks one of programmatic’s quiet workhorses: seller-defined audiences, renamed Curated Audiences by IAB Tech Lab in December 2024. The mechanism did not change; the label did. For performance marketers, that matters because these taxonomy-coded segments are now a default currency for curated deals.
What is actually being bought
A seller-defined audience is not a list of people. It is a numeric segment code attached to a bid request. Publishers or data partners classify readers using first-party data, map those attributes to IAB Tech Lab’s Audience Taxonomy 1.1, and send the IDs in OpenRTB. The taxonomy holds 1,558 nodes: 197 demographic, 497 interest and 864 purchase-intent entries.
In practice, a woman aged 30 to 34 interested in American football could travel as segtax 4 with segment IDs 49, 6 and 608. The buyer learns the segment, not the person. Contextual signals live in site.content.data or app.content.data; audience signals sit in user.data.
Why the rename matters
IAB Tech Lab finalized SDA 1.0 in February 2022, months after Google’s plan to kill third-party cookies made addressability urgent. By December 2024, the standards body admitted the name was limiting. Anthony Katsur, IAB Tech Lab’s CEO, told AdExchanger the framework had been "sitting underappreciated in the corner"; the switch to Curated Audiences reflects that buyers and data partners, not just sellers, can build segments.
Chrome kept cookies in April 2025 and Google retired Topics in October 2025, but these codes survived as a curation vocabulary. They are part of IAB Tech Lab’s broader curation framework alongside taxonomies, the Data Transparency Standard and the SupplyChain object.
What to check before you buy
The main weakness is self-attestation. The 2022 specification itself warned that a provider could label a games cohort as high-net-worth to lift prices. RTB House’s analysis of roughly 135 billion SDA-enriched bid requests from 20 SSPs found about 33% of contextual signals and 75% of user signals failed the specification, mostly via missing taxonomy or segment IDs.
- Ask for the DTS label: it carries provenance, recency, modelling and segmentation criteria.
- Verify segtax values and segment IDs: malformed signals are common.
- Do not treat a taxonomy code as proof of quality: a cooking segment did answer cooking questions more often, but signals still vary.
Yahoo became the first DSP to show DTS labels in its interface in January 2025. If more demand-side tools follow, verification gets easier.
Where curation is heading
Recent moves push toward pooled publisher data and AI-readable deals. Mediavine brought audience data from 18,000 publishers into Index Marketplaces in April 2026. BCN described an agent that matches plain-language briefs against more than 900 audience segments and has PubMatic build the deal. Meanwhile, LiveRamp’s User Context Protocol, now at IAB Tech Lab, fills the same user.data slot with embeddings rather than taxonomy IDs.
The takeaway for growth teams: curated audiences are not disappearing, but the burden of verification sits with the buyer. Ask for the DTS label, inspect the segment mapping, and test performance rather than trusting a code.
Source: PPC Land
