Spectrophotometry is a technique used to measure the intensity of light absorbed or transmitted by a substance as a function of its wavelength. This method is commonly used in chemistry, biochemistry, and physics to determine the concentration of a solute in a solution, identify substances based on their absorption or transmission spectra, or study the interactions between light and matter. Spectrophotometry is a versatile and widely-used analytical tool that provides valuable information about the molecular structure and properties of a wide range of materials.