Why do things glow in the dark?

Glow-in-the-dark objects shine because their material stores energy from earlier light and releases it later as visible light. In phosphorescent paint or plastic, light nudges tiny electrons into higher-energy positions. They return slowly, so the glow continues after the room has gone dark.

The most memorable detail is that the color comes from the size of the energy drop. Many older glow paints used zinc sulfide, while newer strontium aluminate can stay bright much longer. A quick rest near a lamp gives the material another store of energy.