Plasma, considered the fourth state of matter, is superheated ionized gas. Plasma is unlike other gases in that it is electrically charged and greatly affected by electromagnetic fields. It is composed of a gas that has an increased or decreased number of electrons within the particles.
Plasma is a gaseous mixture of ions and electrons. As a gas is heated above a critical temperature, electrons are removed from the atoms, causing ionization of the gas. The free electrons mix with the ions, but remain atomically separate. Plasma is considered a fluid, along with gas and liquid, but its electromagnetic characteristics differentiate it from the other two types.
The charge of plasma is approximately neutral because it contains a balanced number of positively and negatively charged particles. Plasma is the most common form of matter in the universe and can be seen on earth in the form of neon signs, lightning and plasma globes. The sun is a sphere of plasma held together by magnetic fields.
A planet known as Gilese 1214 b has an atmosphere composed of water in the form of a plasma. The extremely high gravity and temperature of the planet result in the water being trapped in a plasma state, unlike any observed water on Earth.