The bounce rate reflects both the quality of your traffic and the capacity of your site to retain this traffic. It measures the percentage of people who come to your website and leave right away after seeing no more than one page.
Note that there is no 'right' value for the bounce rate. It is used to compare traffic patterns over time on a given site. For instance, if you redesign your entrance pages and your bounce rate suddenly increase, then it is a sign that your visitors may be confused and unable to navigate the new pages. Seeing that metric go up is an alarm bell telling you that something might be wrong.
Typically a high bounce rate would be caused by two factors:
Have you made changes to your site recently? If your bounce rate goes down afterwards it's a sure way to confirm that the changes are having a positive impact and that your site is better at retaining visitors. Bounce rates over time can be accessed from the main stats menu > TRAFFIC OVER TIME
This helps you figure out if some referrers are sending you bad traffic compared to others. Do you need to re-evaluate relationships with sites that are not sending you high quality traffic? Are your email, affiliate, other marketing campaigns yielding low bounce rates? This metric will help you answer these questions. Bounce rates per referrer can be accessed from the main stats menu > TRAFFIC ORIGIN > Referrers
People may enter your site through a variety of pages ; the bounce rate per entrance page helps you figure out which pages are good at retaining traffic and introducing the visitor into the site, and which ones are leading them away. If a page has a high bounce rate, you need to evaluate its contents: is it optimally organized? Does it contain the right calls to action? Bounce rates per entrance page can be accessed from the main stats menu > NAVIGATION > Entrance Pages
You need to check that the bounce rates are roughly the same across all platforms and screen sizes. If a particular type of OS or browser (or screen size) shows a high bounce rate, then you can be sure that your site is not displaying properly on that OS/browser/screen-size combination, and you need to address the issue urgently. Bounce rates per equipment can be accessed from the main stats menu > EQUIPMENT USED
In the 'Click-Path' column of this report you can see the depth of each individual visit. Visit depths of '1' indicate a bounced visitor, who viewed only one page. Bounces for individual visitors can be accessed from the main stats menu > DETAILS VISITORS