The Abbe number is a measure of the dispersion of light in a material, specifically how much the refractive index changes with wavelength. It is defined as the ratio of the mean refractive index to the difference between the maximum and minimum refractive indices for visible light. A higher Abbe number indicates lower dispersion, meaning the material produces less chromatic aberration when used in optical systems. This value is crucial in the design of optical components like lenses, where clarity and color fidelity are important. Materials with high Abbe numbers, such as certain types of glass, are preferred in applications like cameras and microscopes to ensure sharp images with minimal color distortion.