Level: Beginner
Nearly every media buying decision starts with understanding which pricing model you're actually paying under, since it changes what "efficient" spending even means.
CPM: Paying for Exposure
Cost per thousand impressions (CPM) charges you for visibility regardless of engagement, common in awareness-focused or programmatic buying where reach itself is the goal.
CPC: Paying for Attention
Cost per click charges only when someone actually clicks, shifting some of the platform's performance risk onto itself rather than fully onto you.
CPA: Paying for the Outcome
Cost per acquisition charges based on a completed action — a sale, a lead — which most directly ties spend to your actual business result, though it's not available on every platform or campaign type.
Next step: Use the Sales Letter Writer to make sure the ad copy behind whichever pricing model you're using is strong enough to justify the spend, since a low CPM or CPC still wastes money if the creative doesn't convert once it's clicked.