Beside the “real” visitors coming to your website also automated bots and spiders hit your site. These bots can come from search engines indexing your website or are other automated services checking if new content was added to your site for example. The problem is that these bots can increase the visit number on your website. You actually do not know how many of your visitors are “real” visitors.
Google Analytics created an easy solution for this. Since July 30th you can activate the check box “Bot Filtering” in the “View Settings” of your Google Analytics profile. Activating this check box will filter out all known bots and spiders from your visitor data. See below, where to add the new functionality in your Google Analytics account.
Source: Google Analytics Bot Filtering