If you ask a physicist, he'll define plasma as an ionized gas, a gas that has 1 or more free electrons, which makes it a conductive agent and it responds to electromagnetic fields. Not only that, but he'll tell you that plasma is a distinct phase of matter, apart from solid, liquid, and gas.
All stars (our beloved Cancunean Sun included) are made of plasma, and the space between those stars is filled with plasma.
Plasmas are divided into the following
- Artificial Plasma: The one found in your beloved HDTV set, the plasma ball you loved to look at back in the 80's, the pinky/bluey/purpley glow coming out from neon signs, and rocket exhausts.
- Terrestrial Plasma: Lightning and aurora borealis are the most common examples of terrestrial plasma
- Astrophysical Plama: Stars, solar winds, and nebulae.