Photometry is the science of measuring visible light in terms of its perceived brightness to the human eye. It involves quantifying light intensity, luminous flux, and illuminance, which helps in understanding how light interacts with various surfaces and environments. This field is essential in applications like lighting design, photography, and astronomy. In photometry, different units are used to express measurements, such as lumens for luminous flux and lux for illuminance. Instruments like photometers are employed to carry out these measurements accurately. Understanding photometry is crucial for optimizing lighting conditions in homes, workplaces, and public spaces.