What metric measures how often an ad is clicked after being shown?

The metric that measures how often an ad is clicked after being shown is Click-Through Rate (CTR). CTR is calculated by dividing the number of clicks on an ad by the number of times the ad is shown, known as impressions. This percentage reflects the effectiveness of the ad in attracting user interest; a higher CTR indicates that more users who see the ad are compelled to click on it. This metric is crucial for evaluating the performance of ads, as it helps advertisers understand how well their messaging and targeting are resonating with the audience.

In contrast, the other options serve different purposes. Cost-Per-Click (CPC) measures the cost incurred by the advertiser for each click on their ad, which provides insights into budgeting rather than interaction rates. Impression Rate refers to the number of times an ad is shown relative to the total number of users, highlighting visibility rather than engagement. Conversion Rate tracks how many of those clicks lead to a desired action, such as a purchase or signup, focusing on the effectiveness of the ad in achieving business objectives rather than the initial click. Thus, CTR is the most direct metric for assessing ad engagement.