Positive displacement is a method used in various machines, such as pumps and compressors, to move fluids or gases by trapping a fixed amount and forcing it into a discharge pipe. This process occurs in cycles, where the volume of fluid is displaced with each cycle, ensuring a consistent flow rate regardless of pressure changes. In positive displacement systems, the mechanism can be a piston, diaphragm, or gear that creates a vacuum to draw in the fluid. This technology is commonly found in applications like hydraulic systems, refrigeration, and automotive engines, where precise control of fluid movement is essential.