SEO methodology can be divided into two camps; that which conforms to the guidelines and regulations of the search engines i.e. white hat SEO, and that which does not i.e. black hat SEO. White hat SEO is characterised by pure results which take a longer time to establish but have a lasting prominence. People practicing white hat SEO not only follow the search engine’s rules, they work to the core principle that content is created for users, not for the search engines. As a result, a website topping a search engine’s list through white hat SEO techniques is much more likely to be relevant to the web user.
Black hat SEO is much more underhand. Content is created deliberately for the search engines in order to trick the spiders into thinking that the content they are searching is relevant to the request, thus gaining an inappropriately high rank. What the search engine bots see is not what the web user views. Black hats generally know their site will be penalised or banned when they’re finally discovered and aim to reap top positions in a short space of time, usually in order to make quick money. Black hat SEO is also known as spamdexing, generally referring to all spam techniques that are disapproved of by the search engines.

Avoid the temptations of quick SEO wins
Examples of poor practice:
Bait and switch
Cloaking
Doorway pages
Hidden links
Domain name stuffing
Cross-linking
Auto-generating content
Spamming forums and blogs
Hijacking sites
Link farms
Duplicate content