After successful uploading of the code, the execution of the code makes the LED blink on and off with a small delay in between. Because this happens in an infinite loop, the LED keeps blinking. /* ESP ...

The ESP8266 now has a barebones build environment focused on minimizing code size, as little as 131 bytes to boot up and blink an LED.

On the hardware side, this is exactly what you’d expect: an LED hanging off the digital pin of an ESP8266 module.