Absorbance is a measure of how much light is absorbed by a substance when light passes through it. It is commonly used in fields like chemistry and biology to analyze the concentration of a solution. The higher the absorbance, the less light is transmitted through the sample, indicating that more light has been absorbed by the molecules in the solution. The absorbance value is calculated using the formula A = log10(I0/I), where A is absorbance, I0 is the intensity of the incident light, and I is the intensity of the transmitted light. This relationship helps scientists understand the properties of materials and their interactions with light.