A neon sign is a lighting display made of glass tubes that have been filled with a gas and bent into the shape of letters or decorative designs. When a high-voltage electrical current is passed through the gas, the tubes emit light. Although neon gas was originally used in these signs, several other gases are also used. These gases, along with different tints and phosphor coatings for the glass tubes, produce a spectrum of over 50 brilliant colors. Neon signs can be as simple as a small advertising sign for beer.
