You've probably seen a plasma globe in class or at a novelty shop before. The glass is filled with a low-pressure, inert gas, which becomes ionized by the electric current from the central electrode to form tendrils of plasma.
Understanding plasma may be the answer to our energy crisis. The tendrils of a plasma globe are the cool cousins of the fires within a star, which fusion researchers hope to reproduce on Earth. Read Physics in Action: Plasma Power to learn more about plasmas and fusion reactors.