white hat seo are practices that are accepted to use in order to get better rankings, more traffic etc. these are techniques that are encouraged by the search engines. practices for both white and black hat seo including link building for example, but it is the way in which it's done that makes it good or bad.
Both techniques can get you results, but if you use black hat seo, you run the risk of your website being banned by the search engines. this can happen by using software submission tools for bookmarking sites and directory submissions. if better to do thing manually as you will not be seen as a spammer.