In tangential flow filtration (TFF), the liquid flows parallel to the membrane surface, unlike traditional dead-end filtration where it flows perpendicularly. A portion passes through the membrane as permeate, while larger particles or molecules are retained in the main tangential flow and continuously swept along the membrane. This cross-flow minimizes fouling and cake formation, ensuring stable filtration performance over time – ideal for concentration, diafiltration, or protein purification.