What does Scroll depth mean?

Scroll depth shows how far a user has scrolled down a page. It is most often measured in percentages, for example 25%, 50% or 90% of the page length. This indicator helps find out whether people actually see important content, banners, CTA elements or parts of a product page placed further down. In analytics, it is used to evaluate user engagement and to adjust content or page layout so that key information doesn't go unnoticed.