Advertising is very simple in a lot of ways. Advertisers go where the users go, and users are choosing to spend a lot more time online.
I think the phone is a really personal device in a lot of ways. If you drop your phone or lose it there's a moment of panic. On the other hand there's a lot of control that users have.
I think we have to recognize as an industry that users have a lot more choices and can click away to a lot more media. As a result, the advertising we create really needs to be something users want to see.
Google is a business that gets paid when users want to see - want to click on - the ad. If we show ads that no one wants to see, we don't generate revenue.