It's been a problem that has been an annoyance to webmasters for several years. Referral spam appearing in Google Analytics reports which made traffic statistics inaccurate and raised bounce rates.
This type of spam was generated by either bots visiting your site pretending to have come from another website, or more commonly software firing off fake Google Analytics triggers using your Google Analytics Site ID without even visiting your website.
The aim of referral or referrer spam was to entice webmasters to visit the websites being spammed into their Google Analytics reports, for either a malicious or profit motivated gain.
There have been several workarounds offered to this problem however none of them were completely effective. This rendered Google Analytics reports fairly useless for small sites where a large proportion of apparent visitor traffic was spam.
Now Google has announced that it will remove referral spam automatically. However the removal seems to be filtered after the event, because referral spam will still appear in the real time view.
Some referral spammers have already shifted tactics in response. We have seen several Google Analytics reports where a referring keyword is spammed into the keywords view for a site which the spammers would like webmasters to visit.
In the main Google Analytics reports will now look much cleaner. Webmasters who did not understand the referral spam problem might be surprised at an apparent drop in traffic. For those webmasters it is important to understand that this was never real website traffic.
Another point worth noting is that Google's response to the referral spam problem does not seem to be retrospective. Referral spam still appears in reports generated for time periods before the end of February, however new reports seem to be completely clear of referral spam.
This is good news for webmasters who have been frustrated by the referral spam problem.