Pressure is defined as the amount of force applied per unit area. In other words, it is the force exerted by a substance or object over a given area. The SI unit of pressure is the pascal (Pa), which is equivalent to one newton per square meter (N/m²).

Pressure can be measured using a variety of instruments, including manometers, barometers, and pressure gauges. In engineering and physics, pressure is a critical parameter for describing the behavior of gases, liquids, and solids.

There are many different units used to express pressure in various applications, including pounds per square inch (psi), atmospheres (atm), and torr. It's important to note that different units of pressure may be used in different contexts, and conversions between units may be necessary to ensure accurate measurements and calculations.

Some common examples of pressure in everyday life include tire pressure in cars, blood pressure in humans, and atmospheric pressure at sea level. In industrial and manufacturing settings, pressure is used to monitor and control a variety of processes, such as the compression of gases, fluid flow in pipelines, and hydraulic systems.