Any online presence carries risks. As soon as you engage your market via the Web, aggrieved customers and anonymous detractors can attack you publicly. You may also expose yourself to legal liability and have to monitor your website for abusive content left by others.
On the Web, everyone’s got an opinion—and you probably don’t agree with all of them. Any website that offers comment fields, collaboration, and content sharing will become a target for two main groups of mischief-makers: spammers and trolls.
Spammers want to pollute your site with irrelevant content and links to sites. They want to generate inbound links to their sites from as many places as possible in an effort to raise their site’s rankings or influence search engines. This is only getting worse. According to Akismet Wordpress’s stats found at http://www.akismet.com/stats, SPAM comments have been on a steady rise since they started tracking spammy entries in early 2006.
To combat this, many search engines’ web crawlers ignore any links that have a specific nofollow tag in them, and blogs that allow commenters to add links routinely mark them with this tag. Nevertheless, blog comment spam is a major source of activity on sites; not only does it need to be blocked, but it must be accounted for in web analytics, since spammers’ scripts don’t help the business, but they may count as visits.
In early 2005, Google developed the nofollow tag for the rel attribute of HTML link and ...