Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration, driven by the random motion and kinetic energy of the particles themselves. This spontaneous process tends to equalize the concentration gradient across a medium, resulting in a uniform distribution of solutes. In biological systems, it is a critical mechanism for transport, enabling the exchange of gases, nutrients, and waste products across cell membranes. Physically, it describes the spreading of substances, such as ink in water or gases mixing in the atmosphere, until equilibrium is reached. The rate of diffusion is highly dependent on the temperature and the physical properties of the surrounding medium.