Search engines have rules that they want webmasters and SEOs to follow. These rules don’t have the force of law, and it’s not illegal to ignore them, but search engines can and will ban your site from their results if they catch you violating them.
So called “Black Hat” SEOs are the folks who dare to defy the search engines, and violate or skirt the rules. Some consider it unethical; others consider it a friendly contest between the SEO and the algorithm twisters at the search engines.
We don’t do Black Hat SEO here at SEOSoftware.net, and we don’t recommend that you do either. Aside from the ethical questions, it’s no game for amateurs. Make a mistake, and your sites can be banned from the search engine results, for good. Do that to an SEO client who did not know that you were pushing the rules, and the results could be disastrous.
All the same, we list here some of the popular programs used by Black Hat SEOs. Use them at your peril.