An electric lamp is one of the devices that work by exploiting the thermal effect of electric current. A sealed glass bulb consists of two thick wires. A narrow and long coil of tungsten wire is attached to both ends of it. This coil of wire is called the filament. The bulb is evacuated or filled with an inert gas.
Since the filament is very narrow and long and the resistance of its material is high, the resistance of the filament is very high. As a result, when current is passed through the lamp, a lot of heat is generated and the filament becomes white and gives bright light. Volts and Watts are written on the electric lamps we use.