Every once in a while, you come across an idea where keeping time is a prime concern. For example, imagine a relay that has to be activated at a certain time, or a data logger that has to store values at precise intervals.
The first thing that comes to our mind is to use a real-time clock (RTC) chip. But since these chips are not accurate, we need to keep doing manual adjustments to keep them synchronised.
The solution here is to use network time protocol (NTP). The ESP8266 NodeMCU has access to the internet, so you can get day of the week and precise time within a few milliseconds of Coordinated Universal Time (UTC) for free! And you don’t need any additional hardware circuitry.