How does Mozilla makes money?

This question was passing by my mind when ever I open my Firefox browser(very rarely I do it). But I usually get in to the tasks that I was after and forget the question.

But this time I thought, I should not give up and searched in Google. So,

How does Mozilla makes money?

Mozilla Foundation has a deal with the Google, the Internet giant, under which Firefox Browser provides Google as the default search Engine and has its default search page hosted by Google, thereby contributing to the revenues of Google. 

For this Google pays Mozilla foundation. Another source of income is Voluntary contributions. So this is the way by which Mozilla Foundation runs....

SOURCE :http://www.zdnet.co.uk/news/desktop-apps/2005/02/28/google-keeping-the-wolf-from-firefox-door-39189475/

http://www.firefoxanswer.com/firefox/795-firefoxanswer.html