Referral spam involves making repeated website requests using a fake referrer URL to a website. Its actual purpose is to provide you with data about any interaction to your website, even external, so that you can have an end-to-end picture of what is happening with your marketing efforts. Unfortunately it’s sometimes used by spammers to get you to visit their site. If you see stray data in your reports, or a spike in data from a site which is not yours, it’s most likely referral spam.
The best practice approach to correcting this is to deploy an include filter in your views for Google Analytics. So, essentially, you’ll tell Google Analytics that you only want to see data in your analysis which comes from your website, www.example.com. Any traffic that doesn’t come from www.example.com will be excluded from your data. Should you have more than one website tracking in a view, you’ll want to include both of those hosts, by setting up a host name filter, to capture data from both websites.
Bonus Tip – You should always have an unfiltered view of your data. Right now you probably have the default “All Website Data” view. You’ll want to leave that as is. Simply create a new view and include a host name filter that only includes traffic to your website. This will eliminate the referral spam in your Google Analytics reports.