Endocytosis and exocytosis are two processes used by cells to transport material in and out of the cell. Endocytosis is the process by which a cell takes in material from the outside of the cell, while exocytosis is the process by which a cell sends out material from the inside of the cell. Endocytosis involves the cell membrane engulfing particles from outside the cell and forming a vacuole within the cell. The material is then processed and either used or stored by the cell. Exocytosis is the opposite of endocytosis, in that it involves the cell membrane expelling material from the cell. This material is typically a product that the cell has created, such as proteins, and is released outside the cell.