How do these World-Wide known websites make money?

[crew94y]

I've been wondering how Wikipedia*, Yahoo, Google, Youtube, Facebook and other websites make money. I've also recently heard that Facebook** and Youtube were having financial problems, I see no ads on this pages so I really don't know how they make money and survive.

* I remember a Wikipedia campaign to raise money...
** I've seen some ads on Facebook applications and on the right hand side column. Do they make money out of those? I dont think they can make much money out of those few advertisements.

[TrueTrader]

Well they make money with Pay Per Click advertising, so the ads that show up, are on millions of pages. So when you click the ad, you make facebook money, it is that simple.

So when some one clicks an ad, they pay facebook for that one click.

This is how they make money, pay per click ads.

google owns youtube, so they are fine, and Facebook just got a $200 m loan to upgrade, So they are both fine.