What does click-through rate (CTR) measure?

Click-through rate (CTR) is a key metric in digital marketing that specifically measures the effectiveness of an advertisement by calculating the ratio of users who click on the ad to the number of users who view the ad. This percentage provides insights into how compelling or relevant the ad is to the audience. A higher CTR indicates that more viewers are interested in the ad, suggesting successful targeting and messaging.

This metric is fundamental for assessing the performance of online campaigns because it directly correlates with engagement; the more users click on an ad, the more likely it is to lead to conversions or desired actions. In digital marketing analysis, understanding CTR helps marketers optimize their ad strategies, refine their target audiences, and improve creative content to boost overall performance.

The other choices do not accurately define CTR as they focus on different aspects of digital marketing. Engagement can include a variety of interactions beyond clicks, total impressions reflect how many times the ad was displayed without considering if users interacted with it, and unique reach measures the number of different users who have seen the ad, which does not directly relate to clicking behavior. Thus, option B precisely identifies the nature of CTR.