|This article's factual accuracy may be compromised due to out-of-date information. (May 2015)|
||This article possibly contains original research. (July 2010)|
Referrer spam (also known as log spam or referrer bombing) is a kind of spamdexing (spamming aimed at search engines). The technique involves making repeated web site requests using a fake referrer URL to the site the spammer wishes to advertise. Sites that publish their access logs, including referer statistics, will then inadvertently link back to the spammer's site. These links will be indexed by search engines as they crawl the access logs. This technique does not harm the affected sites, just pollutes their statistics.
This benefits the spammer because the free link improves the spammer site's search engine ranking owing to link-counting algorithms that search engines use.
A new spam is happening in the digital world, especially in Google Analytics data Called Ghost Spam & Referral Spams with 100% bounce rate. Ghost spam traffic directly interact with Google Analytics data with measurement protocol system where as referral spam directly influence website traffic. As a result spammers try to increase traffic to their websites.
As with e-mail spam, referrer spam may be filtered or blocked. A website operator may mitigate referrer spam by preventing search engine spiders from crawling the site logs by moving them to a non-public area such as a password-protected area, by using a robot exclusion file, or by appending the nofollow value to the links.
It is found that while some referrer spam pollutes analytics statistics directly, some spammers actually hit the web server. Filtering referrer spam from analytics tools will hide it from the reports but can still continue to consume server bandwidth. To save server bandwidth spammers can be blocked using for example a .htaccess file.
Because the htaccess solutions require technical expertise, several developers have created tools for non-technical people to block the spam more automatically, specifically for Google Analytics.
- "Referrer Bombing has caused some of my sites to instantly disappear from google SERP". 22 September 2009. Retrieved 2013-11-19.
- Analytics Spam Blocker is a free tool which removes spam from Google Analytics by adding different types of filters.
- Analytics Referrer Spam blacklist on GitHub - a Community-contributed list of referrer spammers under Public Domain (550+ domains, Jan. 2016).
- Semalt, Darodar and other Referrer Spam Explained - Technical overview of referrer spam in Google Analytics: how it happens and what you can do