Light is a fundamental source of energy for all photosynthetic organisms and microorganisms; it is an environmental stimulus of primary importance for all living beings, terrestrial and aquatic, diurnal and nocturnal, prey and predator, as well.
Photobiology is a large discipline that includes studies of both the beneficial and harmful effects of light.
It covers topics from the atomic level to that of ecological communities.
Photobiologists use all of the tools of science to study the chemical and biological effects of light and other non-ionizing radiation.