A colorimeter is a scientific instrument used to measure the concentration of colored solutions. It works by passing light through a sample and measuring the amount of light absorbed by the solution. The more concentrated the color, the less light will pass through, allowing for quantitative analysis of the sample. Colorimeters are commonly used in various fields, including chemistry, biology, and environmental science. They help in tasks such as determining the concentration of pollutants in water or analyzing the levels of specific substances in biological samples. This makes them essential tools for research and quality control.