From the Semrush Blog: Click-Thru-Rates (CTR) Explained

Check out this article from Semrush that gives you a quick and easy-to-digest explanation of what a click-thru-rate (CTR) is, the difference between a CTR paid and organic search, what a good CTR is and more! CTR is good to track, especially in your email marketing and paid advertisements. This tells you more about your engagement and if you're connecting with your audience.