Light Emitting Diodes have become a popular method of lighting in recent years, and are a common source of illumination in the maker sphere. Whether they are indicators, counters, or just power lights. LEDs are polarized in that electricity can only flow in one direction, this is essentially what a diode does, but in an LEDs case, they give off light as well. When connecting LEds, they might light when connected between power and ground, but it’s not suggested to do this. Since LEDs do not regulate voltage, the diode will pass any voltages through itself and sometimes this can damage an LED. It is recommended you use a small resistor, like a 1k in series when you connect an LED to protect it from burning out (see what series wiring means in the next section). You will also notice that LEDs have a longer and a shorter leg coming from them. The longer leg is the anode, and the shorter is the cathode, which means the anode should be connected to the positive side, and the cathode to the negative side. The circuit diagram symbol is below:

LED symbol

Note that the triangle points to the right, to help indicate the direction of electron flow.