This review covers the following contents. 1. preface. 2. light fading mechanism; 2.1 kinetics, 2.2 effect of addenda in emulsion layer. 3. dark fading mechanism; 3.1 fading with electrophilic reagents (H+ and O3), 3.2 fading with nucleophilic reagents (OH-, SO32-, HSO3-, S2O32-, CN- and residual coupler.)