If you are getting a high bounce rate, have a look at your list of top referrers (sites that send traffic to your page). One that is appearing near the top of many lists is a site called semalt.com.
This is basically a spam site.
It’s role is to send a web crawler to your site, generating fake traffic, and alerting you to their analytics and SEO services. All this traffic bounces straight off your site, and skews the stats for real visitors. They are never going to buy anything or take an interest in your services, so it is pointless to include them in your web traffic figures.
This is just one of a number of spam referral sites, which may be more or less malicious, and you can avoid their visits appearing in your stats by creating a custom filter which specifically excludes those sites.
And by the way, don’t be fooled into using their own site removal tool, as this causes more problems than it solves and for some users has caused their whole analytics record to crash.