what is benefit of facebook's owner of this site?

[Naval k]

I want to know benefit of owner of free social natworking sites example as facebook, myspace etc.

[734]

It may be free to us, but there are a lot of companies and people who advertise through these sites.
For example, on myspace there are always random advertisements that pop up, and there are a few on facebook too. These companies pay the owner of these free social networking sites, and that's how these owners make money off the sites.