For over two decades the subject of laser-induced phase transitions in semiconductors has generated considerable interest. This field arose originally in the context of semiconductor annealing, a technologically important process aimed at repairing the damage to semiconductor crystals caused by dopant atom implantation. The conventional method for this process is thermal annealing the slow baking of a semiconductor in an oven. In the heated sample the increased mobility allows defects and dislocations to diffuse to the surface. In the 1970s, a similar effect was produced by irradiating a doped semiconductor with a short laser pulse. Although laser annealing of semiconductors has not replaced thermal annealing in industrial semiconductor processing, the discovery of laser annealing opened up a new and exciting chapter in the study of light-matter interactions: the use of light to alter the structure of matter.