Radiometry is the science of measuring electromagnetic radiation, including visible light. It focuses on quantifying the power of radiation emitted, reflected, or transmitted by objects. Radiometric measurements are essential in various fields, such as astronomy, meteorology, and environmental science, to understand energy transfer and radiation effects. Key radiometric quantities include irradiance, which measures power per unit area, and radiant flux, which quantifies the total power of radiation. Instruments like photometers and radiometers are used to collect data, helping researchers analyze light behavior and its impact on different materials and environments.