SEO is the abbreviation for Search Engine Optimization. A so-called Black Hat SEO knows everything in the area of the optimization of search engines. However, it uses its knowledge to break the rules of the search engine on purpose. Its aim is to get a good position for the websites which he takes care of, but not caring of any dubious methods like cloaking, doorwaypages, automatic redirections and agglomeration of links or crosslinks. These methods of overoptimization of a website are successful for a short range of time, but there is still the danger of getting eliminated from the index of the search engine. Every customer should consider some steps and precautions before settling for SEO. Ask the SEOs for references. Inform yourself in forums about the SEOs which would come into consideration. Don’t ever choose a SEO which creates shadow-domains. This is a definite hint that they’re talking about a Black Hat SEO.