After understanding the connection making on bread board we connected our first output device- LED on Arduino board’s digital output pin 13, On the micro controller pin 13 acted as positive terminal and GND- Ground act as zero or negative terminal. (blinking aurdino led) it was blinking because the the reset code used was blink. The Coding for this command was - // the setup function runs once when you press reset or power the board void setup() { // initialize digital pin LED_BUILTIN as an output. pinMode(LED_BUILTIN, OUTPUT); } // the loop function runs over and over again forever void loop() { digitalWrite(LED_BUILTIN, HIGH); // turn the LED on (HIGH is the voltage level) delay(1000); // wait for a second digitalWrite(LED_BUILTIN, LOW); // turn the LED off by making the voltage LOW delay(1000); // wait for a second } * Here the words – HIGH & LOW in digitalwrite means ON