Diffusion in biology is the process of movement of molecules from an area of high concentration to an area of low concentration. This movement continues until the concentration of the molecules is equal throughout, a state called equilibrium. Diffusion is a form of passive transport and does not require the input of energy by the cell. It is essential for the movement of substances in and out of cells and is responsible for the movement of various substances, such as gases and small uncharged molecules, into and out of cells
. There are different types of diffusion, including simple diffusion and facilitated diffusion. Simple diffusion occurs without the help of transport proteins, while facilitated diffusion involves the movement of molecules across the cell membrane with the help of carrier molecules or protein channels
