Argon is a commonly used gas used to fill incandescent light bulbs. It increases bulb life by preventing the tungsten filaments from deteriorating too quickly. Other gases such as helium, neon, nitrogen and krypton are also used in lighting.
The gases used in light bulbs are known as inert gases. An inert gas is non-reactive and extremely resistant to chemical change. Inert gases can either be elements or compounds. Due to their inherent stability, inert gases such as argon and nitrogen do not allow a filament to catch fire in a light bulb. Other examples of usage of an inert gas include packing food with nitrogen to prevent spoilage and storing historical documents under argon to resist degradation.