Phosphorescent materials are substances that can absorb light and then re-emit it over an extended period. Unlike fluorescent materials, which emit light only while exposed to a light source, phosphorescent materials continue to glow even after the light source is removed. This property is due to the way these materials store energy, allowing them to release it slowly. Common examples of phosphorescent materials include zinc sulfide and strontium aluminate. These materials are often used in glow-in-the-dark products, such as toys, watch dials, and emergency signs. Their ability to glow in the dark makes them useful for safety applications and decorative items.