Buy cheap domain, make a good website on it, then sell it on flippa or forum. This thing can make you lot of money if you know how to make good website.
I think the definition is already given by other members. I just to tell one more thing that, website flipping is very good business and will get you huge profit.
A website flipper does not necessarily buy a domain and build a website. That is a way to make a few bucks. Some of the best flippers buy established sites that have some decent content but are either not marketed properly (i.e. not getting enough traffic) or have decent traffic but are not being properly monetized. They improve the website and then sell it. That is where the real money is.
LOL! I read the title and thought it's some kind of new online service. Thanks for the info. Learned something new.