The gas most commonly used in light bulbs is argon, often combined with other gases like nitrogen. Traditionally, incandescent light bulbs contained a tungsten filament, which glowed when electric current passed through it. To prevent the filament from oxidizing and breaking, inert gases such as argon are used to fill the bulb, creating a low-pressure environment that prolongs the filament's lifespan. Recently, energy-efficient lighting options like fluorescent and LED bulbs have gained popularity, with some containing different gases or using different technologies, yet argon remains a fundamental element in incandescent lighting designs due to its stability and effectiveness.