The document discusses emerging technologies for interactive digital out-of-home advertising, including Bluetooth Low Energy (BLE) beacons, QR codes, NFC, augmented reality, and Google Glass. It analyzes the properties and potential of these technologies for reducing friction in user interactions with billboards and other outdoor displays. Key advantages and challenges of each technology are considered, such as whether they require downloading an app, proximity needed for interaction, and industry support. The document concludes with tips for using these interactive technologies effectively in out-of-home advertising campaigns.