A sensor is an element which can turn a physical outer stimulus into an output signal which then can be used for further analysis, management, or making decisions. People also use sensors like eyes, ears and skin for gaining information about the outer world and act accordingly to their aims and needs. Sensors can be divided into many categories according to the measured parameter of the environment.

Usually, every natural phenomenon – temperature, weight, speed, etc. – needs specially customised sensors which can change phenomena into electric signals, usually the voltage, that could be used by microprocessors or other devices. Sensors can be divided into many groups according to the physical nature of their operations – touch, light, an electrical characteristic, proximity and distance, angle, environment and other sensors.

• Touch Sensors;

• Light Sensors;

• Optical Sensors;

• Electrical Characteristic Sensors;

• Proximity and Distance Sensors;

• Angle & Orientation Sensors;

• Environment Sensors;

• Other Sensors;