Facilitated diffusion is a process that allows substances to cross cell membranes with the help of specific proteins. Unlike simple diffusion, which occurs directly through the lipid bilayer, facilitated diffusion uses channel or carrier proteins to transport molecules like glucose and ions across the membrane. This process does not require energy, as it relies on the concentration gradient, moving substances from areas of higher concentration to areas of lower concentration. This method is essential for cells to maintain homeostasis and acquire necessary nutrients. For example, aquaporins are specialized proteins that facilitate the movement of water, while ion channels help regulate the flow of charged particles. Overall, facilitated diffusion plays a crucial role in cellular function and communication.