Click Through Rate (CTR) is one of the most important terms for webmasters who have added ads to their website or blog. While most advertising companies display the click through rate some do not. Bidvertiser for instance does not display the CTR of the ads in the statistics (only in the summary but not for individual ad units). CTR is one of the key elements in comparing advertisers and optimizing ads on websites, for pay per click programs that is. Other key elements are overal earnings and cash per click (cpc).