In Star Trek, a phaser is an energy weapon that fires focused beams from handheld and ship-mounted units.
The name is short for “phased energy rectification,” and phasers appear throughout the franchise in many forms. Hand phasers are standard equipment for Starfleet personnel, while larger phaser arrays are built into starships and space stations. Their settings can be adjusted for different effects, including stunning, heating, or disintegrating a target.
Phasers are often confused with disruptors, which are another major Star Trek weapon category commonly associated with Klingon, Romulan, and other non-Starfleet forces. Phasers also differ from photon torpedoes: phasers project energy, while torpedoes are physical launched weapons containing antimatter and other systems.
The technology’s appearance changes between series, but its basic role remains consistent: a controllable directed-energy weapon used for defense, combat, and sometimes technical work.