Diffusion is the movement of a substance from an area of high concentration to an area of low concentration . Diffusion happens in liquids and gases because their particles move randomly from place to place . Diffusion is an important process for living things ; it is how substances move in and out of cells .
Coffee keeps you awake due to the caffeine in it. Caffeine is considered a psychoactive drug which energizes people by releasing a chemical in the body.
