Photoluminescence is a special kind of luminescence, which can absorb light energy then release the energy in light, mostly abbreviated as PL. It covers any material containing phosphors that will absorb light energy and then release that energy in the form of light.
In a simple word, photoluminescent is a kind of light-lead lighting, different to electronic-lead lighting(LED) or chemical-lead lighting.
There are two types of photoluminescence: fluorescence and phosphorescence.
Fluorescent materials absorb light and then emit light instantaneously under condition of no continuous energy supplying, short as to 10-8 second and unable to distinguish by human eyes. They are commonly seen in a TV screen or computer monitor.
Phosphorescent materials absorb and store light, then emit visible light slowly over time. There are many glow-in-the-dark products containing phosphorescent materials in the market nowadays, from mobile phone covers to toys. If you have ever seen any of these products, you know that they all have to be "charged", sounds like a storage battery. You hold them up to a visible or UV light for a few minutes, and then take them to a dark place where they glow for several hours.