Avinash over at Google blog discusses the Bounce rate — “while metrics like visitors show the number of people who came to your site, bounce rate will tell you how many of those people were unimpressed and left your site without taking any action (not even dignifying the site with a single click!).”

1. To find out where your visitors are coming and which sites sends visitors with highest bounce rate. Login to you Google Analytics account, go to "Traffic Sources", click on "Referring Sites," and boom!

2. To investigate the reasons, go to “Content” label and click on "Top Landing Pages" report. You can see different pages of your website on the left and the corresponding bounce rates on the right.