A plasma is a collection of charged particles formed from a gas or solid material. Plasmas are found on earth in neon signs, fluorescent lamps, lightning, flames, rocket exhausts, around re-entering space vehicles, and in research laboratories, as well as in manufacturing systems.
Stars are plasmas as well.
One goal of engineers who study plasmas is to produce a miniature star on earth. This would be one controlled thermonuclear fusion. If this is successful, the human race will have a source of energy of virtually unlimited extent, with nearly inexhaustible supplies of fuel. In industry, plasmas are used for processing of materials for etching, depositing coatings, synthesizing new materials, as well as for cutting and welding and refining of base metals. It is likely that future semiconductors, for example, will have to be etched with plasmas, in order to make linewidths of less than l micron.