Click-through rate (CTR) in online advertising, refers to the number of people viewing a web page who view and then click on a specific advertisement that appears on that page. Click-through rates measure how successful an ad has been in capturing users’ attention. The higher the click-through rate, the more successful the ad has been in generating interest. It helps the advertiser website owner support the site through advertising dollars measured in cost-per-click. A click-through rate helps digital marketers measure the efficacy of a variety of online marketing campaigns. It may be used with a variety of media, such as display advertisements, email advertising, and paid search.