Originally Posted by MSD

There were two types of energy weapons used in the Star Wars universe, plasma weapons and blasters. Blasters (from pistol sized through ship-mounted heavy lasers) used two power sources. One was a battery, which produced the energy required to ionize spin-sealed Tibanna gas (a more stable form than exists in nature, and the primary export of Cloud City) and emit these ionized particles. The beam itself was composed of high-energy ionized particles focused into a coherent "beam," and the light was produced by the photoelectric effect as ionized gas toward the outside of the particle beam returned to its ground state.