Relay does not trigger Its my first attempt to work with relay
I tried to test my relay with this simple code

int Relay = 2; void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  pinMode(Relay,OUTPUT);
}

void loop() {


  digitalWrite(Relay,HIGH);
  delay(1000);
  digitalWrite(Relay,LOW);
  delay(1000);
}




Connected to 
IN -> Digital 2
GND -> GND
VCC -> 5V

The only thing is happened is the LED of the relay blinking in every sec. but can not hear the clicking sound from the relay box or testing with a multimeter's diode function the two(NC and COM) OUTs aren't close
I tried to test other relays(from the same type) but does not do anything else.

thank you for your help
What can be wrong?
NC is "Normally Connected" - this contact is connected to COM ("common") if coil of the relay is not powered - the relay is disconnected.

NO "Normally Open" is connected to COM when the coil of the relay is powered - the relay is connected.

Some relays have the coil powered when the signal from MCU is LOW.

If the coil of the relay doesn't click, but the signaling LED lights up, then VCC is not connected. Check if you plugged the wire really to 5 V on Arduino side.