What is the use of U shaped tube?

A U-shaped tube, often referred to as a U-tube manometer, is used to measure the pressure difference between two points in a fluid system. It consists of a tube bent in the shape of a "U," filled with liquid (usually Mercury or water), which shows the height difference between the two columns of liquid. This height difference can be converted into a pressure measurement, making it a valuable tool in various applications, such as HVAC systems, fluid mechanics experiments, and pressure monitoring in various industries.