Pinocytosis is a cellular process in which cells take in small amounts of liquid and dissolved substances from their surrounding environment. This process is often referred to as "cell drinking." During pinocytosis, the cell membrane invaginates, or folds inward, to form a small pocket that engulfs the liquid. Once the pocket is formed, it pinches off to create a vesicle containing the ingested fluid. This mechanism is essential for cells to obtain nutrients and maintain their internal environment. Unlike phagocytosis, which involves the uptake of larger particles, pinocytosis is a non-specific process that allows cells to sample their surroundings continuously.