Optical Stimulated Luminescence (OSL) is a technique used to date materials, particularly sediments and minerals. It measures the amount of light emitted from a sample when it is stimulated by light, which indicates the last time the material was exposed to sunlight or heat. This method is commonly used in fields like archaeology and geology to determine the age of artifacts and geological formations. The process involves collecting samples, usually quartz or feldspar, and exposing them to a specific light source. The emitted luminescence is then analyzed to calculate the time elapsed since the last exposure. OSL is valuable for understanding historical timelines and environmental changes.