The document discusses why mobile ads don't work as effectively as apps. It notes that people find mobile ads more intrusive than desktop ads and that the small screen size of mobile devices makes ad placement difficult. The document then outlines the top categories of smartphone apps and argues that marketers should focus on creating engaging apps that add value for consumers rather than buying mobile ad space. It provides tips for developing effective apps, such as adding convenience, unique features, social elements, incentives, and entertainment.