Absorption spectroscopy is a technique that is commonly used in analytical chemistry to measure the concentration of a particular substance in a sample by measuring the amount of light that is absorbed by the sample at specific wavelengths. This method is based on the principle that different molecules will absorb light at different wavelengths due to the presence of specific chemical bonds or functional groups. In absorption spectroscopy, a sample is exposed to a beam of light at different wavelengths, and the amount of light that is absorbed by the sample is measured using a detector. By comparing the absorption of light by a sample to a standard curve or reference sample, the concentration of the target substance in the sample can be determined. Absorption spectroscopy is widely used in various fields such as environmental monitoring, pharmaceutical analysis, and biochemistry, due to its simplicity, sensitivity, and versatility. Some common types of absorption spectroscopy include UV-visible spectroscopy, infrared spectroscopy, and atomic absorption spectroscopy.