once you have about 500-1000 unique visitors per day to your site *at least* before you can start to make real money. You can make chimps change from day one from your 50 hits, but this article is targeted at those that have a larger audience, or perhaps are constructing a business plan (either real or in your head) and would like to know how to go about monetising your website. If you get more then 1000 unique visitors a day chances are you already make money from your site (if not you should be!)
paid either on cost per click (CPC)
Some have you click their site full of afilliate banners!
So its a click for their own commercial site plus they get paid for each click on their adds there.