Halogen is a type of incandescent lamp. It has a tungsten filament just like a regular incandescent that you may use in your home, however the bulb is filled with halogen gas. When an incandescent lamp (one which produces light by heating a tungsten filament) operates, tungsten from the filament is evaporated into the gas of the bulb and deposited on the glass wall. The bulb “burns out” when enough tungsten has evaporated from the filament so that electricity can no longer be conducted across it. The halogen gas in a halogen lamp carries the evaporated tungsten particles back to the filament and re-deposits them. This gives the lamp a longer life than regular A-line incandescent lamps and provides for a cleaner bulb wall for light to shine through.