// assigning a name is for attached by pin 3 with a led.
int ledPin = 3;

// assigning a name is for attached by pin 0 with a analog.
int analogPin = 0;

// value for calculate the output pin
int val = 0;

// put your setup code here, to run once:
void setup() {

  // make the led's pin as output
  pinMode(ledPin, OUTPUT);

  // setup serial communication at 9600 bits per second.
  Serial.begin(9600);

}

// put your main code here, to run repeatedly:
void loop() {
  
  // get the out pin
  val = analogRead(analogPin);

  // print out state of the led pin
  Serial.println(val);

  // re-maps a number from output pin to 8 bits (0 to 255)
  val = map(val, 0, 1023, 0, 255);

  // writes an analog value (PWM wave) to a output pin
  analogWrite(ledPin, val);

}