NodeMCU is a Wi-Fi microcontroller board which is an open source IoT platform.
It runs on the ESP8266 Wi-Fi Soc from Espressif Systems, and hardware which is based on the ESP-12 module. Lua scripting language is used by the firmware.
It is built on the Espressif Non-OS SDK for ESP8266 and it is based on the eLua project.
You can program the device using the Arduino IDE or ESP8266 SDK.
It is development board for ESP8266, which is wifi chip with a 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.
This device has 9 digital pins out of 17 GPIO pins. It has only 1 analog pin.
It has 3V output pins, a 5V output pin is not available so you can use Vin pin as 5V for sensors.
The board has a mini-USB port that is used to program the board and also for giving power.
NodeMCU Pin Names and GPIO Numbers
|Pin Names on NodeMCU Board||ESP8266 Internal GPIO Pin Number|