Three types of lightsticks in five colours
A lightstick, also called glowstick is a transparent plastic tube which contains chemical fluids that are held apart in two compartments. If the lightstick is broken, the chemicals mix, which results in an reaction that emits light but not necessarily warmth. This phenomenon is called chemoluminescence.
Lightsticks have various purposes: they are used in the 
military, but are also used for entertainment at parties 
and concerts.