A sensor is a device that measures a physical quantity. An Actuator is a device that alters a physical quantity. In electronic systems, sensor often produces a voltage that is proportional to the physical quantity being measured. The voltage may then be converted to a number by an analog-to-digital converter (ADC). A sensor that is package with an ADC is called a digital sensor, whereas a sensor without an ADS is called an analog sensor. A digital sensor will have a limited precision, determined by the number of bits used to represent the number (this can be as few as one). The actuator too, it’s commonly driven by a voltage that may be converted from a number by a digital-to-analog converted (DAC). An actuator that is package with a DAC is called a digital actuator.
