Is fire a type of plasma?

Fire is not a type of plasma. A plasma exists when so much heat has been added to a substance that the atoms are separated from the electrons and the mixture is ionized. This changes the electrical properties enough to distinguish the mixture from a gas.

Fire is a reaction between the outer electrons of a substance and the surrounding oxygen. Although this requires heat for ignition, the amount of energy necessary is far less than that required to initiate and sustain a plasma. In a fire, the inner electrons are not disturbed, whereas in a plasma, nearly all the electrons are free.