Interfacing Arduino uno with PIR motion sensor

1const int led = 9; // Led positive terminal to the digital pin 9.              
2const  int sensor = 5; // signal pin of sensor to digital pin 5.               
3const  int state = LOW;            
4const int val = 0;                 
5
6void  setup() { // Void setup is ran only once after each powerup or reset of the Arduino  board.
7  pinMode(led, OUTPUT); // Led is determined as an output here.    
8  pinMode(sensor, INPUT); // PIR motion sensor is determined is an input here.  
9  Serial.begin(9600);      
10}
11
12void loop(){ // Void loop is ran over and  over and consists of the main program.
13  val = digitalRead(sensor);   
14  if  (val == HIGH) {           
15    digitalWrite(led, HIGH);   
16    delay(500);  // Delay of led is 500             
17    
18    if (state == LOW) {
19      Serial.println("  Motion detected "); 
20      state = HIGH;       
21    }
22  } 
23  else {
24      digitalWrite(led, LOW);
25      delay(500);             
26      
27      if  (state == HIGH){
28        Serial.println("The action/ motion has stopped");
29        state = LOW;       
30    }
31  }
32}
33