The conversion of light into kinetic energy, which initiates movement in plants, e.g. phototropism and heliotropism, and the ability to mimic nature's ability to cause movement in bulk materials using light energy has been the source of great and increasing interest to scientists leading to the Nobel Prize winning molecular machines. In this chapter, discussion will concentrate on the utilisation of light to create kinetic energy and hence movement, often in conjunction with another stimulus such as heat, pH or an ionic species.