Glossary
CPM
The price of a thousand ad impressions. Display, video, push and pop traffic is mostly sold this way. CPM = spend / impressions × 1000. Your creatives decide how many of those impressions become clicks.
Also called: cost per mille, cost per thousand, PPV.
On a CPM source you pay for eyes, not clicks. A $2 CPM with a 1% click-through rate is $0.20 per click; the same CPM with 0.2% CTR is $1 per click. That is why creatives are tested first on CPM traffic.
PPV (pay per view) is CPM from the publisher's side: a site is paid per thousand views of the ad it shows. Some networks also sell traffic per view of a full-page pop.
Related terms: CPC, CTR, Real-time bidding, Display advertising.