Reference · OOH terms
The OOH advertising glossary
Plain-English definitions that preserve the line between observed delivery, modeled exposure and measured outcomes.
Terms with their limits attached.
- Attribution
- A method for relating modeled exposure to an outcome. Stronger designs estimate incrementality rather than report association alone. Read the guide →
- Billboard
- A roadside OOH structure category that can include large bulletins, smaller posters and digital displays. Read the guide →
- CPM
- Cost per thousand impressions: cost divided by impressions, multiplied by 1,000. Read the guide →
- Digital OOH (DOOH)
- Digital delivery on out-of-home displays across billboard, transit, street-furniture or place-based environments. Read the guide →
- Frequency
- The average number of exposures among the people reached. Read the guide →
- Gross rating point (GRP)
- A derived planning measure equal to reach percentage multiplied by average frequency. Read the guide →
- Impression
- A defined estimate of exposure opportunity; the exact meaning depends on the method and reported unit. Read the guide →
- OOH
- Out-of-home advertising: media encountered outside a person’s home across public, travel and venue environments. Read the guide →
- Opportunity-to-see
- An estimated opportunity for a person to be exposed to a medium, not proof of attention or recall. Read the guide →
- Place-based
- OOH organized around a venue or place context outside the other major format categories. Read the guide →
- Proof-of-play
- A record that a digital creative was scheduled or displayed at a stated time and location. Read the guide →
- Reach
- The number or percentage of a target audience exposed at least once. Read the guide →
- Street furniture
- Street-level OOH structures such as shelters, kiosks and benches. Read the guide →
- Transit
- OOH media associated with vehicles, stations, shelters and airport environments. Read the guide →
- Viewable or viewed impression
- A metric that must be interpreted through its governing standard, thresholds and measurement method. Read the guide →
What the sources support.
Claims below reproduce the scope of the page contract. Derived items show their calculation.
- verified
Geopath describes U.S. OOH audience measurement as a modeled system combining multiple data resources rather than a direct count of every viewer.
- verified
Geopath defines reach as the number or percentage of a target audience exposed at least once and frequency as the average number of exposures among those reached.
- verified
OAAA reported 2025 U.S. OOH format revenue of $6,723.5 million for billboards, $1,683.2 million for transit, $491.7 million for street furniture, and $557.9 million for place-based media.
How to use the glossary
Definitions are deliberately narrow. Follow the linked field guide for formulas, examples, source context and limitations.
Sources for this page
- GeopathCurrent methodology pageGeopath Audience Measurement Methodology (opens in a new tab) ↗
Used for: Modeled U.S. OOH audience measurement and the use of multiple data resources.
- GeopathCurrent fundamentals pageMeasurement Fundamentals: Reach and Frequency (opens in a new tab) ↗
Used for: Definitions of reach and average frequency in OOH audience measurement.
- OAAAApril 20262025 OAAA MegaBrands (opens in a new tab) ↗
Used for: 2025 U.S. OOH revenue totals and shares by billboard, transit, street furniture and place-based formats.