Stef Simmons, UCL Mathematical and Physical Sciences/Flickr (CC-BY 2.0)
Getting excited can kick a person’s energy to a higher level. At the nanoscale, strange almost-particles called excitons do the same trick.
In a crystal, thin film or even some liquids, an incoming particle of light can slam into an electron, bumping it to a higher energy level and leaving a hole at the energy level where the particle had been. The exciton is the excited electron paired with the resulting hole and can move energy in two ways: by physically hopping to a new molecule or transferring energy almost like an antenna transmitting a signal. Either way, the movement is quick, with the longest-lasting exciton existing for just a few milliseconds.