Click-through rate (CTR) is a ratio of the number of users who click on a specific link to the total number of users who view a page, email or advertisement. Click-through rate can be used to measure the success of online advertising campaigns, email campaigns and keywords. Generally the higher the CTR, the more effective the marketing campaign.
The Click-through rate of an ad campaign, for example, is the number of times a click is made on the ad, divided by the number of times the ad is shown or "served" (also called impressions), expressed as a percentage.
CTR = Number of click-throughs / Number of impressions × 100 (%)
- Click-through rate on Wikipedia