A pressure gauge is an instrument used to measure and display the pressure of a gas or liquid within a system. It provides real-time readings, typically in units like psi, bar, or kPa, allowing operators to monitor and maintain safe operating conditions. Pressure gauges are essential in a wide range of applications, including industrial machinery, HVAC systems, water treatment plants, hydraulic equipment, and automotive systems. Common types include analog dial gauges, digital gauges, and bourdon tube gauges, with materials and designs suited for various pressure ranges and environmental conditions.