When you rank higher in search results, you get more clicks. Ideally, many of those people will stay on your website. Some of them, however, are going to quickly leave and return to the search results page. This is known as "bouncing" and it's a problem because it often signifies that your site did not give them what they were looking for. You ranked well for SEO and for the terms that they were using, but your site did not deliver in some fashion. The percentage of users who quickly leave your page is reported in analytics as your bounce rate. High bounce rates can undercut your efforts and it's important to ask yourself what is going wrong.