Blackhat = Bad SEO that Google don't want. They can kick you out of the SERP's Whitehat = Good SEO --> That's what Google wants!
One example would be building a site that shows one thing to the visitors while another is cloaked that shows keyword rich text to the spiders that crawl your website. It's a form of cloaking, it gets a lot more complex but that's the most basic form.
You want to stick with the practices that Google likes. Keep everything out in the open. Put main keywords in the title tags and on the text of the page and get links in from real sites. You can get banned from Google search results by using anything considered Black Hat. Stay away from link farms - sites that are built just to link sites to each other.
If any true Black Hatter got banned from anywhere they would be back very quickly with a new account. Black Hat's don't follow anyone's TOS. They will do whatever they have to to make money and bend rules. Please realize that most Black Hatters do not promote illegal activities so don't get the wrong idea.
It is too easy to get banned by your ISP or a forum for blackhat techniques, while with a little more effort you can do your white hat techniqes with no worries.
WhiteHat - http://en.wikipedia.org/wiki/White_hat (read the Search Engine Optimization part) BlackHat - http://en.wikipedia.org/wiki/Black_hat (read the Search Engine Optimization part) BlueHat - http://www.bluehatseo.com/
Yeah, dont use Blackhat methods. They may work for a little, but Google will catch you and your site will be removed from Google permanently.
BH writing content using the names of your competitors to rank for those and steal some of their traffic - very effective method btw. WH Write content that has value. I really however do not believe there is any such thing as WH. It´s all different shades of grey. The moment you build a site and focus on methods to rank higher, you end up compromising your content in order to please Google rather than your visitors.
Black colour hat seyo duns by evil mans and womons and man-woman mix things make lot money and gettings big cares ande sexy woman girlfrunds. White hat seo done is by good hearts people who make little money. "What is socially acceptable may change tomorrow, but what is common sense will remain the same" - Anonymous