CPM is a traditional online marketing metric in which companies pay for views/listens/downloads of their advertisement. CPM stands for ‘cost per mille, i.e. ‘cost per thousand’, so a CPM campaign is an advertising campaign in which an advert is played to X 1000s of impressions.
The advert can be ‘baked-in’ into the recording itself, which means it cannot be removed or changed, or can be placed at a particular timestamp using a dynamic ad insertion system, which allows the ad to be changed as needed.
These timestamps are commonly assigned to one of three categories; pre-roll, mid-roll and post-roll.