Optically 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 makes OSL valuable in fields like archaeology and geology for determining the age of artifacts and geological events. The process involves collecting samples, usually quartz or feldspar, and exposing them to specific wavelengths of light. The emitted luminescence is then analyzed to calculate the time elapsed since the last exposure. OSL is a reliable method for dating materials ranging from thousands to hundreds of thousands of years old.