Bounce rate is the share of users who entered a page and left it without any further interaction. A high value often signals that the content does not answer what the visitor was looking for, or that the ad promised something the page fails to deliver. It has to be read sensibly, though: on a blog post where someone read the text and left satisfied, a high bounce need not be a problem. Note: in GA4 the classic bounce rate has been replaced by an engagement measure (engaged sessions).