Emerging applications such as smart cities, autonomous vehicles, or smart metaverse, all rely on embedded systems that are engaging with the physical environment through sensors. That means a home that monitors your activities and health status, learns your habits and preferences, and automatically controls lighting, air conditioning, and more. One of the pillars of success for these emerging applications is an efficient and robust mechanism for sensing the physical world. Recent advances in wireless technologies present new promising possibilities to harness the wireless infrastructure in and around buildings and cities to act as a non-intrusive sensing platform. In effect, this network of wireless devices creates an ocean of radio waves that interact with each other and the environment in complex ways. This talk will focus on how to convert any commodity wireless device into an individual sensor by mapping their wireless reflections to relevant physical and behavioral measurements in the context of human sensing, object tracking, and indoor localization. We will then conclude this talk with a glimpse of ongoing research at UIUC iSENS lab on embracing the sensing capability of wireless signals for a wide range of applications, from enabling safe and efficient autonomous driving to enabling remote forest sensing for wildfire monitoring.