Welcome to the world of SEO

SEO techniques are categorized by several as belonging to two broad categories: techniques recommended by search engines as belonging to a good design and techniques not approved by search engines, refereed to as spasm. Accordingly those who utilize them are categorized either as white hat SEO or black hat SEO.

This does not mean that the two have different ethics but rather that they use opposite modes of doing business. Those categorized as wearing white hats tend to provide results that last for a longer time than those produced by black hats. The last ones now that their site will eventually be band from search results but until that moment provide somewhat better results.

An SEO method, practice or routine is well thought-out as white hat if it conforms to the guiding principles of the search engines and involves no fraud.
White hat recommendation is usually summed up as making the content for the users, not for the search engines, and than assuring that the spiders, have easy access to it rather than trying to game the algorithm. White hat SEO promotes accessibility.

Black hat SEO try to develop rankings in a way and using methods that are not tolerated by the search engine they use hidden or colored texts in order to obtain better ranking or use redirecting from one page to another.

Search engines treat with severely such cases of sites using black hat methods. They usually reduce their ranking or totally remove them from the result list.