This lecture by Prof. Ted Rappaport discusses the wireless industry's transition to millimeter wave and sub-terahertz frequencies, exploring the opportunities and challenges for future wireless networks. The presentation covers the potential of terahertz frequencies, the move towards energy-efficient wireless networks, and the impact on data rates and power consumption. Various concepts such as spectrum horizons, experimental radio licenses, and network offloading policies are explored, highlighting the importance of energy sustainability in future wireless communications.