Node MCU is an open-source IOT platform that is built around a very inexpensive System-On-chip (SOC) called ESP8266. The name “Node MCU” is made with the combination of Node and MCU, here Node means microcontroller and MCU means Unit. So, Node MCU is a microcontroller unit that is based on ESP-12 and ESP- 12E hardware.
It supports serial communication protocols i.e. UART, SPI, I2C, etc. Using such serial protocols we can connect it with serial devices like I2C enabled LCD display, Magnetometer HMC5883, MPU-6050 Gyro meter + Accelerometer, RTC chips, GPS modules, touch screen displays, SD cards, etc.
NodeMCU has 128 KB RAM and 4MB of Flash memory to store data and programs.
Node MCU is based on open source Lua-based firmware which is perfect for IoT applications and other conditions where wireless connectivity is required.
As you are aware, Arduino UNO is a microcontroller board with an 8-bit ATmega328P. microcontroller, similarly Node MCU is a development board with ESP8266.
If you know, we have many WIFI enabled boards available for IoT applications but here,we are introducing NodeMCU because:
NodMCU is based on ESP8266 chip which very inexpensive.
It is easy to make IOT applications using NodeMCU.
The pin connection of NodeMCU is very simple.
It can be used in any application that require it to connect a device to local network or internet.
Esp8266 have high features which makes it an ideal module for IoT.