int LDR = 0; //analog pin to which LDR is connected, here we set it to 0 so it means A0 int LDRValue = 0; //that’s a variable to store LDR values int light_sensitivity = 500; //This is the approx value of light surrounding your LDR

void setup() { Serial.begin(9600); //start the serial monitor with 9600 buad pinMode(13, OUTPUT); //we mostly use 13 because there is already a built in yellow LED in arduino which shows output when 13 pin is enabled }

void loop() { LDRValue = analogRead(LDR); //reads the ldr’s value through LDR Serial.println(LDRValue); //prints the LDR values to serial monitor delay(50); //This is the speed by which LDR sends value to arduino

if (LDRValue < light_sensitivity) 
  {
    digitalWrite(13, HIGH);
  }
else
  {
    digitalWrite(13, LOW);
  }

}