The wiring shown below will make the LED (Light Emitting Diode) light up. The Arduino is only used as a power supply. No program (so-called sketch) needs to be uploaded to the Arduino for this tutorial. Note that the Arduino still needs to be connected via a USB cable in order to provide it with power. The 220 Ohm resistor (color code: red-red-brown) is needed to limit the current through the LED in order to avoid it from burning out. The polarity of the LED is important. The longer lead is called anode and needs to be connected to the positive voltage while the short lead (called cathode) needs to be connected towards ground. If the LED is connected in reverse the LED will not light up.
Tutorial
