The NodeMCU is an ESP8266 WiFi based microcontroller board that helped overcome some of the difficulties associated with several versions of boards based on the ESP8266 WiFi module/chips from Espressif. As the popularity of Arduino boards increased, the demand for boards which comes embedded with some of the add-ons used with the Arduino increased. One of the most popular add-ons were the WiFi modules which are used to connect Arduino boards to the internet.
https://www.campuscomponent.co....m/products/esp8266-n