“Black Hat” techniques are unethical methods that some Web site owners use to get their site listed on search engines. Here's a list of four common techniques.Keyword stuffing: Keyword stuffing is the overuse of keywords in a piece of content. Generally, this is repeating the same keywords over and over just to achieve a higher search engine ranking.Invisible text: Quite a few cheap sites use this tactic, which involves making keywords to be the same color as the background, so readers can't see the massive amounts of keywords, but search engine spiders can.Doorway pages: These are pages that regular visitors cannot see, but search engine spiders can. They are used to trick the search engines so that the site gets a higher ranking. Not only do they go against the rules, but they also hurt the visitor's experience.cloaking: It refers to the practice of presenting different content or URLs to users and search engines.