One common description of plasma is to describe it as the fourth state of matter.
We normally think of the three states of matter as solid, liquid and gas.
For a common element, water, these three states are ice, water and steam.
The difference between these states relates to their energy levels.
When we add energy in the form of heat to ice, the ice melts and forms water.
When we add more energy, the water vaporizes into hydrogen and oxygen,
in the form of steam. By adding more energy to steam these gases become ionized.
This ionization process causes the gas to become electrically conductive.
This electrically conductive, ionized gas is called a plasma