Plasma is a gas-like mixture of positively and negatively charged particles. As matter heats up, the magnitude of their kinetic energy increases. Because they energy is so high, not only have they broken free of their attractive forces as in liquids, but they are so free that they are traveling at extraordinary speeds. Random collisions with other particles cause these particles to break apart into charged particles. The only places on earth this takes place is in controlled situations, such as in fluorescent mercury light bulbs. Stars, nebula and the Sun are other places where this state of energy can physically take place.