Lasers come in various types, each defined by their gain medium. Common types include solid-state lasers, which use a solid material like ruby or neodymium-doped glass; gas lasers, which utilize gases such as helium-neon or carbon dioxide; and semiconductor lasers, often found in devices like laser pointers and CD players. Another classification is based on the laser's output characteristics. Continuous-wave lasers emit a constant beam, while pulsed lasers release energy in short bursts. Each type serves different applications, from industrial cutting to medical treatments and telecommunications.