Diffusion is the process by which molecules spread from areas of high concentration to areas of low concentration. This natural phenomenon occurs in gases, liquids, and even solids, driven by the random motion of particles. For example, when a drop of food coloring is added to water, it gradually spreads throughout the liquid until evenly distributed. In biological systems, diffusion is crucial for processes such as cell respiration and nutrient absorption. Cells rely on diffusion to transport essential substances like oxygen and glucose across their membranes, ensuring proper function and survival. Understanding diffusion helps explain many natural and industrial processes.