Audience Taxonomy

An audience taxonomy is a standardized vocabulary for describing audience segments — "Demographic > Age > 25-34", "Interest > Auto > Hybrid/Electric Vehicles", "Intent > Travel > Booked Within 30 Days". The taxonomy lets a data provider, DSP, and SSP refer to the same segment by the same ID across systems, so a buy targeting "fitness enthusiasts" actually reaches the same people regardless of which data graph supplies the impressions.

The dominant taxonomy is the IAB Audience Taxonomy, currently at version 1.1 (2022). It uses the "segtax" envelope (a 16-bit code) to identify which taxonomy a segment ID belongs to: segtax=4 is IAB Audience Taxonomy 1.1, segtax=5 is IAB Content Taxonomy 2.2, and custom taxonomies use values ≥500.

Different taxonomies coexist on the wire. A single bid request can carry segments tagged with multiple segtax codes — IAB AT 1.1 for demographic basics, a vendor-specific taxonomy for higher-fidelity behavioral signals, and a publisher-specific taxonomy for first-party segments. DSPs evaluate each against the buyer's targeting brief.

Trillboards uses two namespaces: IAB AT 1.1 for taxonomy-mappable signals (broad demographic and intent buckets) and a Trillboards-specific segtax=600 for computer-vision-unique signals like cohort composition and attire archetype that have no IAB equivalent.