Do not try this at home kids! Black hat SEO are tactics we advise you to steer clear from. Black hat SEO is when so called SEO experts use unethical SEO techniques. For example, hiding text on a web page by disguising it as the same colour as the background. This technique is used to trick search engines into crawling through keywords that cannot be seen by the human eye. Never use black hat techniques as Google will find out and penalize your website. If you do get found out the penalty may be a reduction of your ranking in search engines or eliminating your database altogether.

The most famous example of a website using black hats SEO and getting caught was BMW in 2006. Their punishment was to be removed from Google for using unethical practices. But they were eventually allowed back after apologizing and removing any black hat SEO.