A pressure gauge is a device used to measure the pressure of gases or liquids in various systems. It typically consists of a dial or digital display that shows the pressure reading, which can be in units such as pounds per square inch (psi) or bar. Pressure gauges are commonly found in applications like automobiles, industrial equipment, and HVAC systems to ensure safe and efficient operation. These gauges work by sensing the force exerted by the fluid against a diaphragm or Bourdon tube inside the gauge. As pressure increases, the diaphragm or tube bends, causing a needle to move on the dial or a digital readout to change. This allows users to monitor pressure levels and make necessary adjustments to maintain optimal performance.