LDR is a light-sensitive barriers. This is the nature of the LDR value detainees will change when exposed to light. In the light of the dark (low intensity), the value of the prisoners will be and vice versa if the light hit the light (high intensity) then the prisoner will be small.
So the size of the resistance of the LDR depends on the intensity of light incident on the surface. With the existence of such properties is very suitable for use as LDR sensor light switch on digital circuits.
