In olden days before the bulb was invented, people used candles, but it was dangerous because it may burn and harm people. Thomas A. Edison is credited with inventing the light bulb. He tried on many metals. Finally, he used carbon filament, which allowed it to last longer. When electricity flows into the filament, it heats up and glow. That's how electric bulb is made. Other than electric bulb, Thomas invented voter machine, generators, etc.