Black Hat Search Engine Optimization are those SEO techniques which are deemed to be clever, sneaky, deceptive, underhand and even dishonest and generally practices that are not endorsed by the search engines or to break search engine guidelines, such as misrepresenting content, buying links, spam indexing, cloaking, link baiting, keyword stuffing, data mining, link spamming, doorway pages, content generating, article rewriting, and even page rank hijacking. Black hat SEO webmasters appear because of the nature of search engines. And a known fact is that more than 92% of black hat SEO websites make revenue by Black hat seo.

Black Hats see search engines as the enemy; deceit is the name of the game, seo’s are constantly looking to expose trickery and penalize guilty sites. These black hat seo breaks search engine rules and regulations and unethically presents content in a different visual or non-visual way to search engine spiders and search engine users. Depending on the competitiveness of a keyword you can see results very quickly. Sometimes within a day - for more competitive terms you can see placement within a few weeks. These are the few ways to increase your website in the top but your site may banned if are caught. Being banned means your site is removed from the index completely from the search engines and the rank gained by these tactics will be finally reduced.

Cloaking will be technique where a webmaster will have two versions of a given web page, one version which is shown the search engine spiders , and one version is shown to the regular web surfer means showing one page to Googlebot and a completely different page to real human visitors.

Interlinking Setting up multiple websites for certain topic and having them all link to each other in order to increase their relevance and subsequently their rankings in the search engines.

Selling Page Rank if you have a high PR website, you sell links from your site to another for cash. This in turn leads to increase the site rank higher in Google.

Invisible Text is the technique of filling a web page consisting of the text that is same color as the background ex: white text on a white background.

Doorway Page is a process of highly optimized web page whose purpose is to direct traffic to target pages using either a code like redirect method or merely by being full of links that direct you to these other web pages and stays as representative to other pages.

Spam Page This page consists of bunch of ads or listings of other sites as doorway pages that a webmaster makes money off of if someone clicks on them.

Keyword stuffing literally the practice of repeating a keyword or important words over and over again on a given web page. If search engine suspect you are just trying to "stuff" webpage repeated content and keywords in the website, there is a good chance they'll penalize you for it.

Buying Expired Domains buying expired websites that had some decent Page Rank in order to try and keep the sites inbound links.

 The above are the few of the black hat seo techniques which in lead in increasing the page rank, traffic and bring the revenue by breaking the rules of optimization. If they are caught will penalized and the sites are banned.