High-Intensity Interval Training (HIIT) is a form of cardiovascular exercise that alternates between short bursts of intense activity and brief periods of rest or low-intensity recovery. This training method is designed to rapidly increase the heart rate and enhance both aerobic and anaerobic endurance. HIIT is effective for burning calories, increasing metabolism, improving cardiovascular health, and building strength in a short amount of time, making it a popular choice for time-efficient workouts.