General properties of flavins -- Photochemistry of flavins in aqueous and organic solvents -- Excited states interaction of flavins with amines : application to the initiation of vinyl polymerization -- Riboflavin as a visible-light-sensitiser in the aerobic photodegradation of ophthalmic and sympathomimetic drugs -- The antiviral and antibacterial properties of riboflavin and light : applications to blood safety and transfusion medicine -- Light-induced flavin toxicity -- Photoinduced processes in the eye lens : do flavins really play a role? -- Blue light-initiated DNA : a repair by photolyase -- Flavin-based photoreceptors in plants -- Flavin-based photoreceptors in bacteria -- Photoactivated adenylyl cyclase (PAC), the photoreceptor flavoprotein with intrinsic effector function mediating euglenoid photomovements -- Mechanisms of light activation in flavin-binding photoreceptors.