CPM – Cost Per Mille – cost per 1,000 impressions.
CPC – Cost Per Click.
CTR – Click-through rate, the ratio of clicks to impressions. For example, if the number of impressions is 15,000 and the number of clicks is 30, then CTR=30/15,000=0.2%.
CPT – Cost Per Thousand – cost per 1,000 unique impressions.