Gizmodo recently published an excellent article with a simple explanation of what we mean by “cold plasma” with emphasis on the recent application of this technology for treatment of onychomycosis (nail fungus).
We’re not talking about biological plasma, that stuff in your blood that holds all the blood cells in place. We’re talking about ionized gas, a fourth state of matter first identified in 1879 by Sir William Crooke — things like lightning, or the plasma arcs the sun spews out. You can find these gases in plasma TV displays, you can use them to create antennae, and if you’re a sci-fi fan, you may dream of plasma firearms as a high-tech weapon.—Gizmodo
I was a little surprised that “they” do not teach k-12 students about the multiple states of matter and only focus on the three (see this discussion, for example). I did not study this in detail but I did hear from a few of my friends who teach in public schools that plasma is not a subject their students are familiar with; similarly, talking with incoming freshmen, students are rarely aware of the fourth state of matter.
For these reasons, I think it is exciting that news sources are slowly picking up on this subject. This way, soon, plasma will be recognizable as something more than the Hollywood special effects tool in crappy science fiction movies.