no such thing as a free lunch

Twenty or thirty years ago, a dictionary was something you bought or went to the library to consult. If you wanted to write down and broadcast your opinions to a potential audience of millions, you spent vast sums of money on advertising in the press or waited till you were famous. If you wanted to see a detailed map of the route from Glasgow to York, the chances are you bought a map and figured it out from there. The idea that all these things could be completely free would have seemed comical back then, and yet here we are with vast resources at the tip of a broadband connection. Music, dictionaries, maps with satellite images superimposed, and free diaries where you can upload pictures, etc., etc., etc. I still find it amazing that we have so much for free (apart from the fairly expensive connection). Sure, I spend plenty of money on the Internet, but what I don't understand is how google.com and others make so much money out of it. google.com gives us no end of free facilities, including a staggeringly good search engine, maps, translation services, and so on, and yet we don't pay google.com a penny. How do they do it? How does it all work? Somebody please explain. (image from http://www.lrz-muenchen.de/~russell01/pictures/cafe.html)