A sensor (or detector) is a device, module, machine, or subsystem whose purpose is to detect events or changes in its environment and send the information to other electronics (frequently a computer processor) or electromechanical components. A sensor is always used with other electronics or components serving as in input device or signal actuator. Sensors may be used to detect and measure temperature, pressure, humidity, voltage, amperage, viscosity, flow, motion, light, the presence of gasses or liquids, vibration, force, speed and more. A thermistor is a type of resistor whose resistance is dependent on temperature, more so than in standard resistors. The word is a combination of thermal and resistor. Thermistors are widely used as inrush current limiters, temperature sensors (negative temperature coefficient or NTC type typically), self-resetting overcurrent protectors, and self-regulating heating elements (positive temperature coefficient or PTC type typically).