What process describes the movement of materials into the cell?

The movement of materials into the cell is best described by endocytosis. This process involves the cell membrane engulfing external substances, folding inwards to form a vesicle that brings these materials inside the cell. Endocytosis is particularly important for the uptake of larger molecules or even whole particles that cannot pass through the lipid bilayer of the cell membrane directly.

In contrast, exocytosis refers to the process of expelling materials from the cell, rather than bringing them in. Osmosis specifically deals with the movement of water across a semipermeable membrane, while diffusion pertains to the passive movement of particles from an area of higher concentration to one of lower concentration. Both osmosis and diffusion can involve the movement of materials in and out of cells, but they do not specifically capture the active engulfing process described by endocytosis.