What is Producing its own light?

Some things make their own glow, while others just bounce light from something else. Think of the difference between a light bulb and a shiny spoon. The bulb creates its own bright light, but the spoon only shines because the sun or a lamp is hitting it.

When we say something is producing its own light, we mean it has the energy to make that glow. Your smartphone screen does this. When you turn it on, tiny parts inside create light that travels straight to your eyes. This is called being luminous.

Most things around you are not luminous. A red apple looks red because it bounces red light from the sun or a lamp. It does not make that light itself. You cannot see an apple in a totally dark room because it has no light to bounce. But you can see a nightlight or a firefly. They are like tiny power plants for light. They use energy to create a glow that works even in total darkness.

Think of a matchstick. Before you light it, it is just wood. Once you strike it, the chemical energy turns into heat and light. That is producing light.