A Sensor is an electronic device that is used to measure some sort of physical parameters (e.g. temperature, pressure, light intensity, etc). The output of an electronic sensor is an electrical signal that is either analog or digital. Processing the sensor’s output can be done in hardware (using discrete electronic elements) or in software (using some sort of microcontrollers or MPUs).

Each sensor has a different working principle depending on the physical construction and the physical parameter it’s actually measuring. The common thing between all sensors is they all convert a physical parameter (such as temperature) to an electric signal. But each one has a specific transfer function (for analog) or a specific communication bus as SPI, UART, etc (for digital). These specific details are demonstrated completely in the datasheet for each sensor with the typical connection diagram and how to interface it.