Project Soli is a Google project that uses radar technology in a small sensor to detect hand motions in 3D space at 10,000 frames per second. The sensor is only 5x5mm and can pick up sub-millimeter finger movements. It uses machine learning to translate intricate hand motions and gestures into commands to control electronic devices through free-hand gestures without the need for physical contact. Some potential applications are in medical devices, gaming, and other consumer gadgets by providing simple gesture-based control.