The filament is the part of the light bulb that produces light. Filaments in incandescent light bulbs are made of tungsten. Whenever an electric current goes through the filament, the filament glows. The reason tungsten is used is because it has the highest melting temperature of any element at 3600K. For a typical incandescent light bulb, the Tungsten filament operates at approximately 2500 Celsius. Hence, the filaments are made of tungsten.