Phasers are fictional energy-based weapons commonly featured in the Star Trek universe. They can be set to different power levels, allowing them to stun or kill targets. Phasers emit a beam of energy that can be adjusted for various effects, making them versatile tools for both defense and offense. In the Star Trek series, phasers are typically used by Starfleet personnel and are an essential part of their equipment. They are often depicted as handheld devices, but larger versions, known as phaser banks, can be mounted on starships. The design and functionality of phasers have become iconic in science fiction.