OSL stands for Optically Stimulated Luminescence, which refers to a dating method commonly used in archaeology and geology. In scientific literature, there are several synonyms used for OSL, including luminescence dating, optical dating, TL dating, and thermoluminescence dating. Luminescence dating is a broad term that encompasses several techniques that use light to determine the age of minerals, fossils, and other materials. Optical dating specifically refers to the use of light to excite electrons and determine the age of mineral grains. TL dating and thermoluminescence dating are closely related techniques that measure the release of energy stored in crystal structures when they are heated, allowing scientists to determine when the minerals were last exposed to sunlight.