Explains the distinction between using the fractal dimensionality and the grain size in describing the change of grain shape when the concept of fractal dimensionality is introduced to the study of the recovery and recrystallisation process in materials. The fractal dimensionality of pure Zn was measured in the recovery and recrystallisation process. From these results a relationship between the fractal dimensionality and energy and a physical interpretation of the dimensionality were deduced.