NodeMCU is an open source IoT platform.It includes firmware which runs on the ESP8266 Wi-Fi SoC from Espressif Systems, and hardware which is based on the ESP-12 module.
The Firmware uses the Lua scripting language. It is based on the eLua project, and built on the Espressif Non-OS SDK for ESP8266. It uses many open source projects, such as lua-cjson, and spiffs.
You can program ESP8266 using Arduino, IDE or ESP8266 SDK. It is development board for ESP8266, which is wifi chip with 32bit microcontroller.
The ESP8266 is a low-cost Wi-Fi microchip with full TCP/IP stack and microcontroller capability produced by Shanghai-based Chinese manufacturer, Espressif Systems.
NodeMCU Pin Names and GPIO Numbers
|Pin Names on NodeMCU Board||ESP8266 Internal GPIO Pin Number|