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A replaceable component that produces light from electricity is called a lamp. Lamps are commonly called light bulbs; for example, the incandescent light bulb. Lamps usually have a base made of ceramic, metal, glass, or plastic, which secures the lamp in the socket of a light fixture. The electrical connection to the socket may be made with a screw-thread base, two metal pins that fit into a receiving clamp, two metal caps or a bayonet cap. The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current, gas-discharge lamps, which produce light by means of an electric arc through a gas, and LED lamps, which produce light by a flow of electrons across a band gap in a semiconductor.

A "sensing bulb" is the temperature sensing device (probe) of a thermometer, RTD, or thermistor.

A thermostat is a component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint by controlling the supply of gas or electricity to the heating or cooling system. Thermostats are used in any device or system that heats or cools to a setpoint temperature. A thermostat operates as a "closed loop" control device, as it seeks to reduce the error between the desired and measured temperatures. Sometimes a thermostat combines both the sensing and control action elements of a controlled system. 

A thermostat exerts control by switching heating or cooling devices on or off, or by regulating the flow of a heat transfer fluid as needed to maintain the correct temperature. A thermostat can often be the main control unit for a heating or cooling system including central heating, air conditioners, as well as kitchen equipment including ovens and refrigerators.