PSI, or Pounds per Square Inch, is a unit of pressure commonly used in various fields, including engineering, automotive, and meteorology. It measures the force exerted by one pound of weight on an area of one square inch. This measurement helps determine how much pressure is applied to surfaces, such as tires or hydraulic systems. In practical terms, PSI is crucial for ensuring safety and efficiency. For example, maintaining the correct PSI in vehicle tires can improve fuel efficiency and handling. Similarly, in industrial applications, monitoring PSI helps prevent equipment failure and ensures optimal performance.