Freeform Button and LED ON OFF tutorial

const int buttonPin = 4; 
const int GREEN =  3;
const int RED =  2;

int buttonState = 0;  
 
void setup() {
  pinMode(GREEN, OUTPUT);
  pinMode(RED, OUTPUT);
  pinMode(buttonPin, INPUT); 
}


void loop() {
   buttonState = digitalRead(buttonPin);
    if (buttonState == HIGH) {
      digitalWrite(GREEN,HIGH);
      digitalWrite(RED,LOW);
      
    } else {
    
    digitalWrite(RED, HIGH);
    digitalWrite(GREEN, LOW);
}
}