NodeMCU ESP8266 V3 Board is an LUA based interactive firmware for Expressif ESP8622 Wi-Fi SoC, as well as an open source hardware board that, unlike the $3 ESP8266 Wi-Fi modules, includes a CP2102 TTL to USB chip for programming and debugging, is breadboard-friendly, and can simply be powered via its micro USB port.
This module is one of the cheapest available wifi-modules in market. V3 or Version3 is the latest version of this module. This tutorial however will facilitate you to connect all the versions of ESP8266 NodeMcu, i.e V1 , V2 or V3.
For makers, having ESP-12 module, rest assured, 12E is no different from its precursor. The only difference : 6 extra GPIOs are present in ESP-12E