Short for PHAsed Energy Rectification, Phasers have been the weapon of choice within the Federation since around 2265 when they replaced the aging laser and plasma cannons. Phasers work by releasing a vast amount of energy using the rapid nadion effect. Rapid nadions are short lived subatomic particles which can liberate and transfer strong nuclear forces within a class of crystals called fushigi-no-umi when energy is channeled through the crystal.
Starfleet has used many models of phaser over the years, but all phasers fall into distinct types. These types usually indicate the general strength and complexity of the weapon, rather than its fire rate or ranges. Phasers come in a variety of sizes, ranging from hand-held weapons and rifles (generally Type I through to Type III), to emitters found on small craft (Type IV to Type VII) such as shuttles, to multi-emitter linear arrays that are found on Starships (Type VIII to Type XII).