On Meta, two figures are easy to confuse. CTR (all) counts every click on an ad, including likes, profile visits and expanding the text, while link CTR counts only clicks that lead to the destination, which is usually the one that matters. In email, CTR measures clicks against emails delivered, and in search it shows how often a listing is chosen from the results.
A high CTR means the message caught attention, but it says nothing about what happened next. An ad can attract many clicks with a curious headline and then disappoint on the landing page. CTR is most useful next to conversion rate and cost per result, which show whether the clicks led anywhere.
