Whoop is a fitness tracker designed to monitor your body's performance and recovery. It uses a strap worn on the wrist to collect data on heart rate, sleep patterns, and physical activity. This information helps users understand their overall health and optimize their training routines. The device provides insights through a mobile app, offering personalized recommendations based on the collected data. Whoop emphasizes the importance of recovery, encouraging users to balance workouts with adequate rest to improve performance and prevent injury.