The term black hat originates from old cowboy movies where the good guys would wear white hats and the bad guys would wear black.
Black hat techniques are unethical search engine optimization strategies. Most of the time these unethical practices are used to boost the rankings of a particular site and sometimes used to drop the rankings of a competing site.
Unfortunately many new bloggers get sucked into using these techniques by tailgating “friends” only to later find that they wish they hadn’t followed those leaders. However, codesucker has written a solid post on his blog Modern Web Development exposing these practices that I would like to recommend to my readers. Read –> What is Black Hat SEO?