Although several advances have been made in the characterization and the mitigation of light-induced degradation (LID), industrial silicon solar cells still suffer from different types of light-induced efficiency losses. This review compiles four decades of LID results in both electronic- and solar-grade crystalline silicon. The review focuses on the properties and the defect models of boron-oxygen LID and copper-related LID. Current techniques for LID mitigation are presented in order to reduce cell degradation and separate copper-related LID from boron-oxygen LID. Finally, the review summarizes recent observations of severe LID in modern multicrystalline silicon solar cells.