Click-Through Rate (CTR)

You paid a bunch of dough to put up banner ads on a popular website's front page. The ads direct those who click on them to come to your Nostril-Trimmers-For-Tall-People-Who-Really-Need-It website. Over the course of this two-week campaign, 10 million banners are flashed. Only 100,000 get clicked upon. Their CTR is 100,000 divided by 10 million, or 1%. Sounds low, but this figure is about standard for most web ad campaigns.

The next math then revolves around those 100,000 clicks...if 5,000 people bought a trimmer which contributed $10 to profits, then the Trimmer company received $50,000 in profit contribution for running those 10 million ads. Was the campaign worth it? Well... it definitely was to the people who have to stand close to those formerly long-nose-haired tall people.