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 a development board for ESP8266, which is a wifi chip with a 32bit microcontroller.
The ESP8266 is produced by Shanghai-based Chinese manufacturer, Espressif Systems and it is a low-cost Wi-Fi microchip with full TCP/IP stack and microcontroller capability.
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.
