#define LED 9 //the pin for the LED
#define BUTTON 7 //the input pin where the push button is connected

int val = 0;  //integer variable "val" used to store the state of the input (button) pin

void setup() { //setup() is called once
  //pinMode() function configures a pin as either an input or an output
  pinMode(LED, OUTPUT); //tell Arduino LED is an output - the "load" of the circuit
  pinMode(BUTTON, INPUT); //tell Arduino BUTTON is the input
}

void loop() { //loop() is called over and over
  val = digitalRead(BUTTON); //read input value and store it
  
  //check whether the input is HIGH (button pressed)
  if (val == HIGH) {
    //digitalWrite() functions outputs a value on a pin
    digitalWrite(LED, HIGH); //turn LED on or high or 5 volts
  } else {
    digitalWrite(LED, LOW); //otherwise turn LED off or low or 0 volts or ground
  }
}