A fog machine is a device that produces a dense vapor resembling fog or smoke. It works by heating a special fluid, usually a mixture of water and glycol or glycerin, which creates a thick mist when vaporized. Fog machines are commonly used in theaters, concerts, and Halloween events to enhance visual effects and create an atmospheric setting. These machines come in various sizes and types, including portable models for small events and larger units for professional use. The fog produced can be colored with lighting effects, making it popular in the entertainment industry, including theater, concerts, and nightclubs.