Sell service/product to anohter website owner
Basically this is about the same as discussed before. The different is the customer of this business. As you know, many people make their own website. But they can not publish the site to internet if they do not have a web server. They internet address can not be found by other people if they did not register their internet name.
So where the money flow here? It from the service that you sell. The service is to register customer domain name to the international regiter, put this database in your server and publish to entire server in the world. This business called domain registration.
Unless you have your own server where you put your internet pages - this is very expensiver - the world would not know your page. Since this service involve heavy IT equipment, some IT businessman make a company called web hosting company. In this company you can put your internet page. You must pay them, ouf course, for every single page your place on their server. If you have a free webhosting that give you some hosting space, I can say if that is not really free. Nothing is free. Whe you register to this free service like yahoo, actually yahoo is starting to approach you using their paid service. And before you go for paid service, yahoo put some advertising on your site for their own benefit. You did not pay at all, but yahoo making money from you :)
So in this business, money come from domain registration service and web hosting service.