There are three types of seo," White Hat", "Black Hat","grey Hat" Main purpose of all the seo is generating leads and sales not only just traffic. White hat seo is the technique of seo which we do under the guidelines of google Black hat is the opposite of white hat which is not according to guidelines of google it could be give you result fast but you will get penalized by google soon by using it. Grey hat is combination of both white and black Hat seo. I usually believe on white Hat seo for my website and always getting a best results.