Comment spam
Also called: blog spam, forum spam or social spam
Comment spam is a blackhat-seo technique that involves the automated posting of comments on Web sites and weblogs. When visitors can comment on articles, a link to a Web site can often be added to that comment. Sometimes links in the comment text itself are also made clickable. Spammers who use comment spam hope to be found better in search engines by doing so.
To combat comment spam, many blog applications have sophisticated filters. In addition, posting a comment often requires filling out a captcha. To discourage spammers from abusing comments, many blogs place a nofollow on outgoing links by default.
In addition to weblogs, forums and social media are also popular targets of comment spammers.
