Im workind in SEO with baclinks and good article and i really want to learn more..
Since everyone has the jokes covered, I'll just answer the Q:
Blackhat: Technically against TOS but needed to get up the search. Artificial backlinks from quality sites.
Whitehat: Within TOS with no artificial links but you won't rank shit.
Lackhat: Shit hat, like a bowler hat, ten gallon hat, Robin Hood with a feather in it hat, my attempts at wearing my technological hat, etc.
Why did you answer this? OP could have done a 2 min google search to get the answer. It almost does not deserve a reply.
If they really wanted to find out the answer they could find it themself.