Tabata workout is a form of interval training designed to get your heart rate up in that very hard anaerobic zone. You train all of your energy systems.It helps you burn more calories both during and after your workouts.
The reason this type of workout works so well is because of the work-to-rest ratio. You get 10 seconds of rest between each 20-second bout of exercise.
That short interval isn't enough to allow you to fully recover, which is one reason it's great for building endurance and getting you in shape.