Digital Out-of-Home

"Digital out-of-home" is the long-form spelling of DOOH. Both terms refer to the same thing: any advertising surface that (a) is a digital display, (b) lives in a public or shared physical space, and (c) is sold and reported as media inventory rather than as signage.

The "digital" qualifier distinguishes this from traditional OOH (vinyl, paper, paint) and the "out-of-home" qualifier distinguishes it from in-home digital channels like CTV and web. The buying motion is converging with CTV — same DSPs, same VAST tags, same brand-safety contracts — but the measurement model is different because the audience is shared, not solo.

The current IAB Digital Out-of-Home Buyer's Guide (revised 2025) standardizes how a single playout is converted to an impression count: a published "audience-on-screen" multiplier per playout, derived from venue audited foot-traffic or, on sensor-equipped screens, from real-time computer-vision counts. Trillboards screens emit the sensor-derived count per playout, so the impression is a measurement rather than a model estimate.

Practical buying advice: ask any DOOH SSP whether they publish a sellers.json, whether their venue taxonomy maps cleanly to OpenRTB 2.6's "dooh" object, and what fraction of impressions are sensor-counted vs. modeled.