This virtual issue of P&P collects some of the many relevant papers published in the Journal on diverse areas of photosensory biology during the last five years. Edited by Francesco Lenci and Jean Cadet Besides being a fundamental source of energy for all photosynthetic organisms and microorganisms, light is an environmental stimulus of primary importance for all living beings, terrestrial and aquatic, diurnal and nocturnal, prey and predator, alike. The importance of light as a stimulus applies for creatures provided with "eyes" and neural networks as well as for aneural life forms like plants, fungi and even unicellular microorganisms, such as bacteria, algae and protozoa.