There's a reason advertisers love Google so much. The company is better than any other when it comes to collecting information about you, its users, and then using that information to serve targeted advertisements on the websites you visit. In Google's case, the trade-off is that you get to use all of its amazing software and all of its great services for free — how evil!
Of course, Google isn't the only company that uses your browsing history and other private data to sell ads.
DO. THIS. NOW. How to stop cell phone companies from secretly selling your info to advertisers