What click-through rate measures
Click-through rate is the share of people who saw an ad and clicked it. It is the first rate in the funnel and the one most directly under the creative team's control: the audience decides whether the ad is shown, the ad decides whether it is clicked. A rising CTR on a steady audience means the message is landing; a falling one on the same audience means fatigue, and it usually shows up two or three weeks before the cost per lead does.
Which clicks count matters. Meta reports "CTR (all)", which includes reactions, comments and profile taps, and "CTR (link click-through rate)", which is clicks to your page. Use the link version; the other one flatters every campaign. Google's CTR is clicks on the ad divided by impressions and needs no such care.


