Plasma, the fourth state of mattar is a highly ionised gas with very high temperatures.
Our fluorescent bulbs, stars, lightning, magic ball etc... are examples for plasma. Plasma is a super conductor where the resistance to the flow of flow of current is zero.
During thunderstorms, Air which is a non conductor changes to plasma in a fraction of a second. Air breaks down into plasma and conducts the the electricity from the cloud to the ground.
It is a state where the electrons are free to move rather than bonding with atoms or molecules like the other three states of mattar. Plasma are the most common in the universe.
Fire, Lightning, Ball lightning, Jets, Polar Aurorae are the examples of Plasma. Rocket exhaust, Spacecraft's heat shield are examples of artificial plasma. Supernova remains are considered to be expanding plasmas.