Proof of play
In practice, for a UK buyer
The paragraph above is the neutral answer. This is the part a vendor glossary leaves out.
The strongest delivery evidence out-of-home can produce, and the reason a DOOH report proves the media ran rather than that anyone saw it. It is a delivery fact, not an audience fact, and a plan that treats proof-of-play counts as reach is overstating by whatever the seller's audience model says.
What this one connects to
Most confusion in media buying comes from two adjacent terms being used interchangeably, so these are the neighbours worth reading next.
Digital out-of-home (DOOH)
Advertising on digital screens in public places — roadside billboards, rail stations, shopping centres, office lifts, gyms. Increasingly bought programmatically by screen, venue type, geography and time of day rather than as a fixed two-week poster site list.
Viewability
Whether an advert was actually rendered in a position where a person could have seen it, measured against an industry threshold — commonly half the pixels for one second for display, two seconds for video.
Evidence provenance
A label attached to a number recording how it was produced — reported by the seller, observed on your own property, estimated by a model, or established by a powered experiment — so its strength travels with it.
Reach
The number of distinct people or households exposed to a campaign at least once, as opposed to the total number of impressions delivered. Usually expressed as a count or as a percentage of a defined universe.
More on measurement and evidence
What you can prove afterwards, and the difference between a number that means something and a number that does not.
45 minutes. Bring a real brief and we compile it live. You describe one audience and watch it compile into seven targeting specifications, each with the score for how much of the definition survived.
Talk it through