A rotary union is a mechanical device that allows the transfer of fluids or gases between stationary and rotating parts of a machine. It typically consists of a rotating component and a stationary component, enabling the flow of substances while minimizing leakage. Rotary unions are commonly used in various applications, including industrial machinery, robotics, and aerospace systems. These devices are essential in systems where continuous rotation is required, such as in turbines or printing presses. By providing a reliable connection, rotary unions help maintain efficiency and performance in equipment that relies on fluid or gas transfer during operation.