Click-through rate (CTR)
From The Yaffe Center
Click through rate (CTR) is the ratio of "number of times an ad is clicked" and the "number of impressions of the ad". A higher CTR indicates that the ad is successful in capturing the person's interest and generated traffic to the company's home page or the landing pages. It is one of the metric to judge the effectiveness of an ad campaign. However, it is not the only metric. An ad is successful if it resulted in a purchase or acceptance of the offer presented in the landing pages. Therefore, CTR in conjunction with conversion rate is a true measure of the success of an online ad campaign.