Plasma is a combination of the free ions and electrons. Plasma naturally occurs in stars (including the sun).
The temperature is so high within the stars, that the atoms break up. Some of the electrons break away from the atoms and turn the rest of the atoms into electrically charged particles called ions.
In a star, this combination of free electrons and ions is called plasma.
The sun and other stars are bright because of the plasma present in them.
Plasma can also be made on earth by transmitting electricity at very low pressure by gases.
The fluorescent tubes and neon sign bulbs for plasma when they are switched on.