There are three types of doing search engine optimization
It is done by strictly following google webmaster guidelines .it is the suggested and best way of doing SEO
2 Grey hat SEO
It is done by overdoing the guidelines of google webmaster guidelines
3 Black hat SEO
It is completely against google webmaster guidelines. And will be banned within a short time when google finds out.
Seo is again divided based on the way of optimizing
It will be teached in the next blog