What process involves engulfing materials in a vesicle?

The process that involves engulfing materials in a vesicle is known as endocytosis. This mechanism allows cells to take in substances from their external environment by wrapping the plasma membrane around the material, ultimately forming a vesicle that brings the material into the cell. Endocytosis plays a vital role in various cellular functions, such as nutrient uptake and immune responses, by facilitating the transport of a wide range of substances, including large molecules and particles.

While phagocytosis and pinocytosis are specific forms of endocytosis—where phagocytosis deals with the ingestion of larger particles and pinocytosis with the intake of liquids—endocytosis as a broader process encapsulates both mechanisms along with others, reinforcing its classification as the primary answer.