The number of people who visit your site but don’t hang around or explore it. Usually you don’t want a high bounce rate because it means people are only viewing one page and leaving. There can a number of reasons for having a high bounce rate, from bad design to lack of relevance or that they found exactly what they came for on the first page (e.g. a specific blog post or contact info). Bounce rates and other information about your sites perfomance can be gathered from analytics packages. It’s hard to say what a desirable bounce rate is without context but, in general, a home page should have a low one, while a blog post might have a high bounce rate because visitors will follow a link, read it and leave. Generally speaking, a bounce rate over 30% is bad and needs attention while a bounce rate under 15% is pretty good and an excuse for a party.
Clear & persuasive calls to action and links which drive visitors to other areas of the site are key to reducing bounce rates.