A light-emitting diode, more commonly known as an LED, is a component that emits light when an electric current passes through it. Today, there is a wide variety of LEDs available in different colors (red, green, blue, yellow, white), as well as multicolored LEDs, such as RGB LEDs, which can display a combination of red, green, and blue.The LED allows current to flow in only one direction, from the anode to the cathode. The opposite direction, where current cannot pass, is called the reverse blocking direction. For this electronic circuit, you will need a 220-ohm resistor, an LED, and a breadboard. // Define the pin number where the LED is connected const int ledPin = 3; // Pin D3 for the built-in LED void setup() { // Initialize the LED pin as an output pinMode(ledPin, OUTPUT); } void loop() { // Turn on the LED (set the pin to HIGH) digitalWrite(ledPin, HIGH); // Wait for 1 second (1000 milliseconds) delay(1000); // Turn off the LED (set the pin to LOW) digitalWrite(ledPin, LOW); // Wait for another second delay(1000); }