Exocytosis is a biological process where cells transport molecules out of their interior. This occurs when vesicles, which are small membrane-bound sacs, fuse with the cell membrane. Once fused, the contents of the vesicle are released into the external environment. This process is essential for various cellular functions, including the secretion of hormones and neurotransmitters. During exocytosis, the cell uses energy to facilitate the movement of these vesicles. It plays a crucial role in maintaining cellular communication and homeostasis. Exocytosis is also important for the delivery of proteins and lipids to the cell membrane, contributing to cell growth and repair.