Instrumentation is measures and controls process variables within a production or manufacturing area. An instrument is a device that measures flow, temperature, level, distance, angle, or pressure. Instrumentation is used in refineries, factories, and vehicles. The most common example of an instrumentation system is a mechanical thermostat which controls a household furnace and room temperature. Instrumentation system is also used as a home security system, consisting of motion detection, switches to detect door openings and simple algorithms to detect intrusion. Kitchen appliances also use sensors for control.