Spam

Link spamming information 

What is link spamming?

Link spam (also called blog spam or comment spam) is a form of spamming or spamdexing that recently became publicized most often when targeting weblogs (or blogs), but also affects wikis (where it is often called wikispam), guestbooks, and online discussion boards. Any web application that displays hyperlinks submitted by visitors or the referring URLs of web visitors may be a target.

Adding links that point to the spammer's web site increases the page rankings for the site in the search engine Google. An increased page rank means the spammer's commercial site would be listed ahead of other sites for certain Google searches, increasing the number of potential visitors and paying customers.

History of link spamming

Link spamming originally appeared in internet guestbooks, where spammers repeatedly fill a guestbook with links to their own site and no relevant comment to increase search engine rankings. If an actual comment is given it is often just "cool page", "nice website", or keywords of the spammed link.

In 2003, spammers began to take advantage of the open nature of comments in the blogging software like Movable Type by repeatedly placing comments to various blog posts that provided nothing more than a link to the spammer's commercial web site. Jay Allen created a free plugin, called MT-BlackList, for the Movable Type weblog tool that attempts to alleviate this problem. Many current blog software now have methods of preventing or reducing the effect of blog spam.

Because of prevention improvements in blog software link spam is now increasingly concentrated on wikis around the World Wide Web including Wikipedia, the largest wiki on the Internet (see [1]). Wiki spam sometimes only appears on a wiki's sandbox page, but is often found defacing multiple pages. The website chongqed.org lists URLs of offending link spammers.

Possible solutions to link spamming

Instead of displaying a direct hyperlink submitted by a visitor, a web application could display a link to a script on its own website that redirects to the correct URL. This will not prevent all spam since spammers do not always check for link redirection but has proven very effective. Redirecting links prevent Google from factoring the link in its PageRank algorithm for that site making the spam ineffective. An added benefit is that the redirection script can count how many people visit external URLs, although it will increase the load on the site.

Another option is for the script to be client-side JavaScript, nofollow, turing tests, or the specific anti-spam methods available in various types of software.