Why is inert gas used in a light bulb?

Inert gases, such as argon or nitrogen, are used in light bulbs to prevent the filament from oxidizing and burning out quickly. These gases create a non-reactive environment that helps prolong the life of the filament by reducing evaporation and the formation of tungsten deposits on the bulb's glass. Additionally, the use of inert gases allows for a more stable and efficient light output.