Linear TV
In practice, for a UK buyer
The paragraph above is the neutral answer. This is the part a vendor glossary leaves out.
The distinction from addressable matters commercially rather than technically. A spot buys everyone watching; addressable buys the households you selected. That makes linear a reach instrument and addressable a targeting one, and it makes the fidelity question different — on linear there is no audience approximation to score, only an audience forecast to trust. UK linear inventory sits behind sales houses and is transacted as booking paperwork rather than through a self-serve API, which is why any platform promising one-click linear television in the UK is describing something else.
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.
Addressable TV
Television advertising where different households watching the same programme at the same time receive different adverts, swapped in at the set-top box or in the stream. It is bought on household attributes and geography rather than on programme and time slot.
Insertion order (IO)
A contractual document committing an advertiser to buy specified advertising from a specified seller at agreed terms. The mechanism by which media that is not bought programmatically is bought instead.
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 channels and formats
The seven things you can actually buy, and the words the sellers use for them.
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