KEY TAKE AWAY POINTS:
LED = Light Emitting Diode
Polarized 2 leads, "big foot" or flat side connects to GND
Usually as a simple digital signal outputer ("digital write pin [ P1] to (1 )")
Usually with a Resistor Friend to limit current
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Resistance value differs for
Different LEDs (color, size, brightness, etc.)
Different voltage supplying the LED
Calculation according to Ohm's Law