White hat SEO:
In search engine optimization (SEO) terminology, White Hat SEO refers to the usage of SEO strategies, techniques and tactics that focus on a human audience opposed to search engines and completely follows search engine rules and policies. For example, a Web site that is SEO optimized, yet focuses on relevancy and organic ranking is considered to be optimized using White Hat SEO practices. Some examples of White Hat SEO techniques include using keywords and keyword analysis, backlinking, link building to improve link popularity, and writing content for human readers White Hat SEO is more frequently used by those who intend to make a long-term investment on their Web site. Also called Ethical SEO.
:Black hat SEO
Black hat SEO is the use of techniques that are unacceptable to search engines to boost a page's position in search results. These techniques are intended to trick search engines into giving pages higher positions in search results, and they have no benefit to site visitors. The goal is to improve search engine result positions no matter what it takes to do it.
Black hat SEO techniques are used for two reasons:
They work — until search engines find out about them and they don't work.
Some people don't understand that black hat SEO techniques can get their sites penalized by or banned from search engines.
Even if search engines can't detect the black hat SEO techniques, competitors of sites that employ black hat SEO techniques can spot them and do report them to search engines.