The melting point of filament of a bulb is very high.

i.                     The bulb begins to glow only when the filament is heated to a high temperature, and it becomes incandescent (bright) without melting.

ii.                    This happens only when the material of the filament has a high melting point.

iii.                  Hence, the material used in the filament of an electric bulb must have a high melting point. For eg. Tungsten (3380⁰C)