First of all, plasma is the stuff of lightning, flame and stars. Plasma is neither solid, liquid nor gas plasma is a fourth state of matter. Sir William Crookes discovered plasma in 1879. Plasma is a state that is formed on matter when a certain amount of particles is ionized. Although solids, liquids and gases are more familiar to us on Earth, over 99% of the matter of the Universe exists as plasma - in stars, like our Sun, or as interstellar matter. Also, the Sun is so hot that the hydrogen and helium of which it is made exists as plasma. Plasma is an electrically charged gas. In plasma, negatively charged electrons have been pulled out of atoms. The atoms are left with a positive electric charge. These positive and negative charges are able to move around freely. Because the charged particles in plasma are free to move, they are able to conduct electric currents. They also respond to magnetic fields, usually in an unpredictable way. Besides, the Northern and Southern lights - aurorae - are created by plasma in the Solar wind responding to the Earth's magnetic field. Particles thrown out from the Sun strike the Earth's atmosphere so hard that they break down gases into plasma, creating the Aurorae. Lightning strikes when air changes from a gas to plasma. Air molecules are quite stable, so this change takes a lot of energy - the result is catastrophic. Some gases change into plasma much more easily. These gases are used in fluorescent tubes, or in the plasma tubes that simulate lightning.
Anyone who took elementary science in grade school recalls the lesson about the three states of matter, right? That was the one where we were told that matter comes in three basic forms: liquid, solid and gas. This works for the periodic table of elements and can be extended to include just about any compound. Except perhaps for whipped cream (that damnable compound continues to