CTR stands for Click-Through Rate, which is a metric used in internet marketing and SEO to measure the effectiveness of an online advertisement or search engine result. It is calculated by dividing the number of clicks an ad or search result receives by the number of impressions it generates, and then multiplying the result by 100 to get a percentage. CTR is a crucial metric as it indicates how successful an ad or search result is in attracting clicks and driving traffic to a website. A higher CTR generally indicates that the ad or search result is relevant and compelling to users, while a lower CTR may suggest the need for optimization or improvement.