Instrumentation is the process of measuring and controlling the physical properties of a system. It involves the use of instruments, such as sensors, transducers, and controllers, to measure and control the system's parameters. Instrumentation is used in many industries, including manufacturing, energy, aerospace, and healthcare. The term 'INSTRUMENT' refers to any device that measures or controls a physical property, while 'AGENCY' refers to an organization or body that has the authority to regulate or enforce certain laws or regulations.