you might wanna read this wiki article http://en.wikipedia.org/wiki/Search_engine_optimization focus on the section on white hat and black hat
nothing to add. thing is fast results give you low priority, as SE's think you use software or another chemistry kinda doorways. when you move slowly - SE' watch organic movement. white hat is organic stuf. but in very competitive fields, where you need to push site up in a week, for example, mobiles, opinions of films or goods, or travels, you have a little time for decision. so, white hat is about time, long lasting development and PERFECT RESULTS on finish.
White Hat is the so called "Good Guy" eg. Ethical Hacker Black Hat is the so called "Bad Guy" Eg. Non-Ethical Hacker Grey Hat is somewhere in between
Nothing is truly whitehat because blackhat starts right when you try to build links instead of getting them naturally. I suppose it would be people who simply did on-site optimization.