Boyle's law states that if you squeeze a fixed amount of gas into a smaller volume, the pressure will increase. This happens because when the volume of a gas is decreased, the particles of the gas have less space to move around. As a result, they collide more frequently with the walls of the container. These collisions create a force that we measure as pressure. So, when the volume decreases and the particles collide more often, the pressure of the gas increases.
