Details on Flashing the lastest firmware and lighting up an LED.
The course contains chapters on developing and IoT application on NodeMCU Dev Kit (Version 1.0 /V2) on a Linux PC.
Node MCU is an open source firmware for ESP8266 SOC based on eLua , a derivative of Lua for embedded hardware.The firmware will work on all ESP - X's ,limited only in terms of breakout for the SOC .It is an ultra low cost module with versions starting at around 3 Dollars (~220 Rs in India) and goes to 8 Dollars (~700 RS) for NodeMCU Dev Kit. The dev kit helps for starters as it has an onboard USB-UART (CP2102) and 3.3v Regulator.
NodeMCU can be considered as a very light weight OS with capabilities of handling the file system and run LUA scripts, a cross platform programming languge for embedded hardware.More details can be found from official Documentation Page