Plasma...the fourth state of matter...not much is known about it.

But matter has so many properties...perhaps there are different state of plasma too?

Anyways why is it a fourth state of matter when all it is ionized gas?

wiki has this on plasma: electrically neutral medium of positive and negative particles

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Now the part I am interested in is the types of research/fields in which plasma is applicable

* electrohydrodynamic coupling: plasma on aerodynamic surfaces used to reduce drag...

what does anyone know about it?

Anyways why is it a fourth state of matter when all it is ionized gas?

Why is liquid a state of matter when all it is, is excited solid (i.e. some molecular forces broken)?

And yes, there are other states of matter (e.g. Bose-Einstein condensate) and sub-states