The criteria and metrics can be classified according to its type and time span. Regarding the type, we can either evaluate these campaigns "Quantitatively" or "Qualitatively". Quantitative metrics may include "Sales Volume" and "Revenue Increase/Decrease". While qualitative metrics may include the enhanced "Brand awareness, image and health" as well as the "relationship with the customers".
Google's search engine marketing is one of the western world's marketing leaders, while its search engine marketing is its biggest source of profit. Google's search engine providers are clearly ahead of the Yahoo and Bing network. The display of unknown search results is free, while advertisers are willing to pay for each click of the ad in the sponsored search results.