Facebook offers both costper click, for which advertisers pay only when users actually click on the advertisement, and costperthousandimpressions, for which advertisers pay based on the number of times these advertisements are displayed on user pages.
MoPub published its fourth quarter 2012 marketplace report which showed strong trends with over 50% gains in just two months in eCPMs (effective costperthousandimpressions). iOS had the benefit of not just capturing higher prices but also had a larger increase at 66% vs.