The phaser is the standard directed-energy weapon of Starfleet, built in hand-held, rifle and starship-mounted forms with adjustable settings ranging from stun to disintegration.
Phasers became the signature sidearm of Starfleet officers from the era of Captain Kirk onward. The name comes from phased energy rectification, and the weapons fire a coherent beam whose effect is chosen by the user, from a stun that renders a target unconscious to settings that heat, cut or vaporize matter outright.
Hand phasers were produced in several types. The smallest, often called a type-1, could be concealed in the palm, while the larger type-2 pistol carried more power and could be fitted with the smaller unit. Phasers were also used as tools, heating rocks for warmth, cutting through bulkheads or being rigged to overload as improvised explosives, a trick used by many crews in tight spots.
Starship phasers work on the same principle at far greater power. They are mounted in banks or long emitter arrays along a ship's hull, giving vessels such as the USS Enterprise a precise beam weapon to complement torpedoes, and Starfleet tactics have relied on them in nearly every era since the 23rd century.