The CPM model refers to advertising bought on the basis of impression. This is in contrast to the various types of pay-for-performance advertising, whereby payment is only triggered by a mutually agreed upon activity (i.e. click-through, lead, sale).
The total price paid in a CPM deal is calculated by multiplying the CPM rate by the number of CPM units. For example, one million impressions at $10 CPM equals a $10,000 total price.