Plasma was the fourth form of matter, which was created by ionizing gases at high temperatures. Plasma was naturally produced in stars, although it could be found in other places in the galaxy and created artificially by electrifying, heating or otherwise energizing gasses. The planet Naboo was known to export plasma as early as the reign of King Ars Veruna. When used in blasters, it was more effective against droids and shields, while the more common concentrated particle beams were more effective against living beings.
BlasTech DC-model blasters from the Clone Wars fired blue, plasma-based rounds, using the ionic charge of plasma very efficiently against droids.
The Zann Consortium used several ships and vehicles equipped with plasma cannons designed to shoot two shots spiraling around each other and inflict massive damage.