Halogen lamps and incandescent lamps belong to the family of thermal radiators, which generate light by heating a tungsten filament.
Halogen bulbs, however, contain halogen gas which reduces wear on the tungsten filament and increases the bulb's longevity and makes it possible to heat the filament to a higher temperature, resulting in more light.
Special heat-resistant glass makes possible to produce very small lamps, like tiny plug-socket lamps.