Kinetic theory or kinetic theory of gases attempts to explain overall properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion. The theory basically states that pressure is not caused by molecules pushing each other away, like earlier scientists thought. Instead, pressure is caused by the molecules colliding with each other and their container. Kinetic theory is also known as kinetic-molecular theory or collision theory.

There are three main components to kinetic theory: