A lightbulb is a glass bulb that produces light when electricity flows through it. Inside the bulb, electricity heats a thin wire called a filament until it glows brightly, or in newer bulbs, electricity passes through special gases or LEDs that produce light more efficiently.

Thomas Edison helped develop the first practical lightbulb in 1879, and it transformed how people lived. Before lightbulbs, people relied on candles, oil lamps, and gas lights, which were dim, smoky, and dangerous. The lightbulb made it possible to read, work, and play safely after dark. Factories could operate at night. Cities became brighter and safer. Students could study after sunset without straining their eyes by candlelight.

Today we use the image of a lightbulb over someone's head to show they just got a good idea, a bright idea. When you suddenly understand something tricky in math class, it feels like a lightbulb switched on in your mind. That cartoon image connects to the real way lightbulbs changed the world: they literally brought brightness where there had been darkness, just like a good idea brings clarity where there had been confusion.