Online advertising pricing models include cost per mille (CPM), cost per click (CPC), and cost per acquisition (CPA). Key metrics for measuring the success of online advertising campaigns include click-through rate (CTR) and conversion rates. There are several methods for calculating important metrics like impressions, clicks, leads, and costs based on available data points for pricing models. Understanding these various online advertising pricing models and metrics is important for evaluating the performance and ROI of paid online advertising campaigns.