The principle of the pressure cooker is very simple, because the boiling point of water is affected by the air pressure, the higher the air pressure, the higher the boiling point. On high mountains and plateaus, the pressure is less than 1 atmosphere, and water can boil at less than 100°C. Eggs cannot be cooked in ordinary pots. When the air pressure is greater than 1 atmosphere, the water will not boil until it is higher than 100°C. The commonly used pressure cooker is designed using this principle. The pressure cooker seals the water quite tightly. The water vapor produced by the evaporation of the water cannot diffuse into the air, and can only remain in the pressure cooker. This makes the pressure inside the pressure cooker higher than 1 atmosphere, and the water must be higher than 100°C. When it boils, a high temperature and high pressure environment is formed inside the pressure cooker, and the rice is easily cooked quickly and is quite crisp. Of course, the pressure in the pressure cooker will not be unlimited, or it will explode.