Air pressure is the force exerted by air on all bodies at all times in all directions. When air moves, it creates a low-pressure area, and air moves from the region where the air pressure is high to the region where the pressure is low. The pressure exerted by air is called air pressure, which is the thrust exerted by air per unit area. The typical pressure at sea level is 1013.25 millibars or 14.7 pounds per square inch. Air pressure is measured using an instrument called a barometer.

Air pressure is responsible for many phenomena in nature, such as the movement of air masses, the formation of winds, and the fluttering of leaves, banners, or flags when the wind is blowing. Air pressure can also be observed in everyday life, such as when a card sticks to the mouth of a glass filled with water and inverted over a sink. The air outside exerts an upward pressure on the index card, which is more than the weight of the water in the glass.

In summary, air pressure is the force exerted by air on all bodies at all times in all directions, and it is responsible for many phenomena in nature. It is measured using a barometer, and its typical value at sea level is 1013.25 millibars or 14.7 pounds per square inch.