Black hat SEO means anything done unethical to the website in Search Engine Perspective. They are nothing but getting unnatural ranking techniques. Though Natural Rankings are time consuming, painful and needs lots of patience on the other hand black hat seo give instant results which are short term based unless you are lucky. I am not in favor of black hat techniques as they are short term based.
Hello... There are many ways to trick search engine spiders into believing they are viewing something they are not.These sites will try spamming,cloaking,hiding keywords by making the background and text the same color as well as many other little nasty tricks. Its just a matter of time before they are caught and then google drops them from the listings for unethical porposes. hope this was helpful... thanks malcolm BIZ-GIANT DIRECTORY
I can't help myself, to quote a little green guy, black hat SEO is "quicker, easier", but it is not as powerful as ethical SEO.
In a way, you could consider any SEO to be blackhat - writing content to include keywords, trading links with people, tweaking the order your content appears in the code, it's all done to unnaturally increase the rank of your page. If you want to take it to the extreme, anything other than starting a page and telling your friends about it and letting it spread "naturally" is unnatural SEO thus blackhat. Of course, nobody actually follows that...