Which element is used in light bulbs as a fire?

"Fire" is exactly what you DON't want inside a light bulb.  If fire was
burning in there, it would burn up the tiny wire that glows to make the
light, and then there would be no more light from the bulb.

Thomas Edison's biggest accomplishment in "inventing" the light bulb
was to FIND a material that could be heated so hot that it would glow
brightly and still NOT burn. 

He tried hundreds of materials.  The one he finally settled on, and the
one still used in incandescent bulbs today, is Tungsten ... Element #74,
a metal that doesn't melt until it's heated to almost 6,200 degrees !