. >> gary kovacks takes the play of john lilly who has also been on the show. and john an ben, so explain do not track. you're not the only web browser that has it. but what's the concept or the idea? >> the concept is simple. we're tracked in everything we do on the web. that information is used for some valuable purposes to help us get a better experience. it's often used to monetize and create additional revenue for people that you don't even know. so the user's data is being used in a way that they don't know. and we find that offensive. so we initiated something in firefox 4, we were the first that put a do not track option in the browser which just gives an opportunity to put up their hand and say don't track me, you cannot sell my information to third parties or use it for purposes other than what i allow you to do. >> you said there are good purposes and bad purposes. am i given the option or how does it work that i allow the good and not the badded? >> today did not track is an opt-in facility. you put in your preferences. the back ends have to accept