Incandescent Bulbs:

* Argon (Ar): The most common gas. It's inert and prevents the filament from oxidizing (burning) too quickly.

* Nitrogen (N2): Another inert gas used to help preserve the filament.

* Small amounts of other gases: These can be added to improve the bulb's efficiency or color temperature.

Fluorescent Bulbs:

* Argon (Ar): Provides an inert atmosphere for the electrodes.

* Mercury Vapor: When energized, mercury vapor emits ultraviolet (UV) light.

* Phosphor Coating: The inner surface of the bulb is coated with a phosphor that absorbs the UV light and re-emits it as visible light.

LED Bulbs:

* Nitrogen (N2): Used to displace oxygen and prevent oxidation of the LED components.

* Other gases: Can be used to improve heat dissipation or create specific color temperatures.

Note: The specific gas composition varies depending on the manufacturer and the bulb's intended purpose.