The process by which a cell takes in surrounding material is known as endocytosis. In this process, the cell membrane engulfs external substances, wrapping them in a membrane to form a vesicle. Endocytosis is crucial for acquiring nutrients, responding to environmental changes, and maintaining cellular homeostasis. Various forms exist, including phagocytosis, for solid particles, and pinocytosis, for liquids. This uptake is essential for cellular function and survival.