What causes an electric light bulb to be hot to the touch?

An electric light bulb becomes hot to the touch primarily due to the conversion of electrical energy into heat energy as the electric current passes through the filament. This resistance in the filament generates heat, which in turn causes the bulb's surface to warm up. Additionally, the glass components of the bulb can also retain heat, contributing to the overall temperature increase. As a result, touching a lit bulb can lead to burns or discomfort due to this heat.