Membrane dynamics refers to the processes that govern the behavior and movement of biological membranes, which are essential structures surrounding cells and organelles. These membranes are primarily composed of a phospholipid bilayer, allowing them to be flexible and selectively permeable. This flexibility enables the membranes to change shape, fuse with other membranes, and facilitate the transport of substances in and out of cells. Key mechanisms involved in membrane dynamics include endocytosis, where cells engulf external materials, and exocytosis, which releases substances from the cell. Additionally, membrane proteins play crucial roles in signaling and transport, contributing to the overall functionality and adaptability of cellular membranes.