Because having plenty of inbound hyperlinks is such an important part of search engine optimization, optimizers are always searching for new ways to obtain new links to their sites. This leads to the use of obtrusive techniques, such as blog spam, guestbook spam, wiki spam, and forum spam. In January, 2005, Google, Yahoo!, MSN and other important sites took a collaborative action against link popularity spam by agreeing on the use of a new tag called the rel="nofollow" attribute. This attribute can be added to any hyperlink to tell search engines not to count it as a vote for the page the link is pointing to. The reasoning behind this attribute is that spammers will stop comment spam, if the links on the comment pages are not taken into consideration in the search engine rankings. (Google 2005.)
Blog spam is a very current topic at the time of writing this paper. Blogs or web logs are online diaries or frequently updated personal web pages. They have become very popular in the last couple of years and therefore have received attention from the SEO community. Most blogs have links to comment pages after each individual post to the diary. Spammers have noticed the opportunity that these comment pages present and as a result have started sending out a lot of spam to those pages, in an attempt to increase the link popularity of their sites. Blog spam is very similar to guestbook spam, which was very popular a few years ago.
Website guestbooks are comment pages, where visitors can freely leave comments, questions and greetings for the site owners and other visitors. Guestbooks used to be a part of almost all personal websites, but have now become rarer. For a long time, guestbook owners have been struggling with spammers, who leave a comment with links to the spammers’ website.
Wiki Spam is another method of gaining link popularity, and it is very similar to blog spamming. Wikis are collaborative websites comprised of the collective works of many authors (Webopedia b). The interesting thing about wikis is that its concept of “open editing” lets anybody edit the content of the pages. It is an easy task to place hyperlinks on the pages as well, which makes it an easy way to increase link popularity. Wikis have to fight spam on a daily basis.
Forum spam is often more subtle than the other link popularity spam methods. In many discussion forums, participants are allowed to add links to their posts and signatures. In most cases, the links are related to the topic. However, spammers can use discussion forums to increase link popularity by sending irrelevant posts, if the forums are not supervised by a moderator, or there are not enough moderators.
FFA is an abbreviation for “free for all”. “FFA refers to webpage scripts that automatically update a links listing when someone submits their URL to it” (JC-Websites). As the name implies, free for all pages are available for anybody to add a link to the directory without it being edited first. FFA pages used to be an easy way to increase link popularity and gain good rankings in the search engines. Search engines started ignoring links from spammy FFA pages a long time ago and they have very little or no influence in the SERPs anymore.