Three lower energy phases of matter are solid, liquid, and gas. Plasmas are the most common form of matter, comprising more than 99% of the visible universe. Everyday forms of plasma are the sun and stars, which are plasmas heated by nuclear fusion, fluorescent and neon lights, lightning?, the [Aurora borealis]?, solar wind, and interstellar nebulae
Sir William Crookes, an English physicist, identified a fourth state of matter, now called plasma, in 1879. The word 'plasma' was first applied to ionized gas by Dr. Irving Langmuir, an American chemist and physicist, in 1929.