Final answer:
Endocytosis is the process by which external materials are captured inside vesicles and brought into the cell. It includes different types like phagocytosis and pinocytosis.
Step-by-step explanation:
Endocytosis is the process by which external materials are captured inside vesicles and brought into the cell. This occurs when the cell membrane folds over the substance, completely enclosing it, and then a membrane-bound vesicle moves the substance into the cytosol. There are different types of endocytosis, including phagocytosis, which is the endocytosis of large particles, and pinocytosis, which brings in fluid containing dissolved substances into the cell through membrane vesicles.