"Bounces" allow you to analyse the tendency of visitors who abandon your site before exploring it.
Indeed, Bounces show how many visits ended with a single page view, that is how many times browsers entered the site, viewed a single page and exited the website.
Bounce Visits are therefore a useful piece of information to gauge users' interest in your website.
In a general sense, if a page has a high number of Bounces, it is worthwhile to analyse in depth all available data in order to investigate all possible causes, in order to be able to optimise the page as necessary and minimise the percent of users that exit your website after viewing it.
Bounces are a very important tool to evaluate the quality of visits, the effectiveness of your website (and its entry pages), and also, to figure out traffic sources that generate targeted visits.
On condition, that is, that one pays attention to contingent factors and relates specific data with other significant parameters, first of all the average time spent on pages (indicative of interest towards the contents on offer) and the visit source (useful to diversify data in connection with traffic sources).
A high number of Bounces becomes more worrysome when the average time spent on your site or on specific pages is less. Longer times are a sure indication of visitors' interests for your proposed contents.
On the other hand, a site or a page with lots of visits originating mostly from Direct Requests will show a higher Bounce Rate than a site or a page which is mostly visited by people coming from a Search Engine.