I think they either make money of ads on their sites, or they just build a strong community and then sell for much money.
Adsense because the people who sign up for free hosting generally have to login via the site so they get a lot of unique visits, also they may offer paid hosting as well If your interested in started one I have freecpanelhosting.net
i think its google ads they place on their site..either this or . as andrej said..they first require you post atleast xx amount of posts on their forums..and then you get around 100 megs of space..and very limited bandwidth..i used to have one before..but its pretty much limited in every sense..
Mainly Ads, I agree,... also They should offer paid plans aswell. SO they have 2 sources on income. Without those, they would be gone very fast
But what abt Ads free hosting ? How they earn ? And if I am starting a free hosting biz how can I put adsense inside my clients site ? What happen if they start ant sites against TOS ?
You're probably talking about the free hosted sites being free of ads, but we're talking about having ads within the user panel (like on statcounter.com). Most free hosting sites are driven by ads like these (within the user panel) and some offer paid hosting as well (like http://www.wickedzone.net ) Try it out and see if you like it...
Some of the free hosting sites also put ads on the users sites, which will make them some money. I don't think there is much advertising in it though as most people that will signup to a free web hosting account will do it as a personal page or something and will therefore not promote it that much meaning a lack of traffic.
Now I am planning to put adsense in free hosting service.But which script I can use for this : I mean the script that I should give the clients ?