The acronym HIIT stands for High-Intensity Interval Training. This fitness training method involves alternating between short bursts of intense exercise and periods of rest or lower-intensity activity. HIIT is popular due to its effectiveness in burning calories and improving cardiovascular fitness in a shorter time frame compared to traditional steady-state workouts. Research also indicates that HIIT can boost metabolism and improve muscle endurance. It is an efficient way to enhance fitness levels for individuals with tight schedules, making it a favored choice among fitness enthusiasts.