Pressure measurement is the analysis of an applied force by a fluid, liquid, or gas on a surface. Pressure is normally measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure and display pressure in an integral unit are called pressure meters or pressure gauges or vacuum gauges. The most widely known used gauges is the Bourdon gauges which is a mechanical device, which both measures and indicates.