Sensors & Modules
The sensors convert a physical quantity into a corresponding voltage. They are used to measure physical properties like pressure, temperature, force, acceleration, location, motion, light intensity, humidity, air pressure, etc.
The term transducer is often used for sensors. They capture the change in the environment variable.
Sensor modules have extra electronic circuitry along with a sensor that helps interface them with microcontrollers.
In embedded systems, sensors and actuators are used for controlling the system. Sensors are connected to the input port and Actuators are connected to the output port.