(partial) Important units in the SI system. Introduction. Fundamental photophysics. Light sources. Absorption and wavelength selection. Measurement of radiation. Excited states and their relaxation. Photochemical reactions and energy transfer. Bioluminescence and chemiluminescence. Halobacterium. Photosynthesis. Photomorphogenesis. Light-dependent rhythms. Light-dependent movement responses. Molecular basis of vision. Biological effects of ultraviolet radiation. Index.