blink the onboard LED at pin 13
This program blinks the onboard LED [at pin 13] in an incremental order, with a delay of 2sec between each iteration.
And on the serial monitor[Tools > Serial Monitor] you can see when the blinking starts, stops and no.of times it blinks.
blining pattern:
blink
blink blink
blink blink blink
blink blink blink blink
...
Serial monitor output:
blinking started.....blinking stopped (1)
blinking started.....blinking stopped (2)
blinking started.....blinking stopped (3)
blinking started.....blinking stopped (4)
...
Sources:
https://www.arduino.cc/en/Reference/pinMode
https://www.arduino.cc/en/reference/serial
https://www.arduino.cc/en/Reference/DigitalWrite