Endocytosis:This is a broader term for the process by which cells absorb molecules (such as proteins) from outside the cell by engulfing it with their cell membrane.
Phagocytosis:This is another type of endocytosis where a cell engulfs large particles or whole cells, either as a defense mechanism (like white blood cells eating bacteria), or for nourishment.
Exocytosis:This is the opposite process to endocytosis. It's when materials are expelled out of the cell using vesicles that fuse with the plasma membrane.