A gas laser is a type of laser that uses a gas as its medium to produce light. In these lasers, an electrical current or another energy source excites the gas molecules, causing them to emit photons. The emitted light is then amplified and can be focused into a coherent beam. Common examples of gas lasers include the helium-neon laser and the carbon dioxide laser. These lasers are widely used in various applications, such as in medical procedures, industrial cutting, and scientific research, due to their ability to produce high-quality, focused beams of light.