Almost 99 percent of all matter in the universe is plasma. It's not common on Earth because of its extremely high temperatures; but somewhere like the sun, it's the norm. On Earth, you find it in lightning, among other places.
Plasma cutters are not the only devices to harness the power of plasma. Neon signs, fluorescent lighting and plasma displays, just to name a few, all rely on it to get the job done. These devices use "cool" plasma. Though cool plasma cannot be used to cut metals, it has tons of other useful applications. Check out How Fluorescent Lamps Work to learn more.
What is Plasma?
If you boost a gas to extremely high temperatures, you get plasma. The energy begins to break apart the gas molecules, and the atoms begin to split. Normal atoms are made up of protons and neutrons in the nucleus (see How Atoms Work), surrounded by a cloud of electrons. In plasma, the electrons separate from the nucleus. Once the energy of heat releases the electrons from the atom, the electrons begin to move around quickly. The electrons are negatively charged, and they leave behind their positively charged nuclei. These positively charged nuclei are known as ions.
When the fast-moving electrons collide with other electrons and ions, they release vast amounts of energy. This energy is what gives plasma its unique status and unbelievable cutting power.