Diffusion coefficients are numerical values that describe how quickly particles, such as atoms or molecules, spread out in a medium, like a gas or liquid. A higher diffusion coefficient indicates that particles move more rapidly and spread out more easily, while a lower coefficient suggests slower movement. These coefficients are essential in fields like chemistry, biology, and materials science, as they help predict how substances will mix or react over time. The diffusion coefficient depends on various factors, including temperature, pressure, and the properties of the medium and the diffusing substance. For example, in gases, diffusion occurs faster than in liquids due to the greater distance between particles. Understanding diffusion coefficients is crucial for applications such as drug delivery in pharmaceuticals and pollutant dispersion in environmental science.