Deduplication
In practice, for a UK buyer
The paragraph above is the neutral answer. This is the part a vendor glossary leaves out.
The reason a cross-channel plan needs one exposure record rather than seven reports. Without it, a launch that buys the same households on television, streaming and out-of-home reports three audiences that are substantially one audience, and the number that reaches a board is wrong by a wide and unknowable margin. Deduplication at launch matters more than at any other moment, because a launch buys the same people repeatedly by design.
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.
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.
Frequency capping
Limiting how many times one person or household sees the same advert within a given period, to control wear-out and wasted impressions. It is set per campaign, per channel or — rarely — across channels, and that granularity is what decides whether the cap means anything.
Exposure ledger
A single record of advertising exposures across every channel, keyed on whichever of four identifiers a channel can supply — an opaque household key, a hashed advertising id, a consent-based id, or a postcode sector — with per-key legal grading.
More on targeting and identity
How an audience is described to a seller, and how much of the description survives. Most of the honest difficulty in media buying lives here.
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