A high bounce rate means that the webpage isn’t fulfilling the customers expectations, so they leave. That could be accidental clicks, a misalignment on headlines or poor content quality.
It is worth considering what method of measuring bounce rate you use. Newer platforms like Nudge improves the accuracy of the measure of the bounce rate by excluding people that actually engage with the page and read it from the bounce rate calculation. In older measurement systems this would not be included.
A high bounce rate can also increase traffic acquisition and customer acquisition costs, because more traffic is required to hit targets. High bounce rates also decrease conversion rates and other downstream metrics.
SEO can also be impacted, if Google deems that the content quality is low and not driving results.
This is part of our Guide to Bounce rate.