NodeMCU is an open source Iot platform. It includes firmware which runs on the ESP8266 Wi-Fi SoC from Espressif Systems, and hardware which is based on the ESP-12 module. The term "NodeMCU" by default refers to the firmware rather than the development kits. The firmware uses the Lua scripting language.See the NodeMCU Wikipedia page for more details.
I have paired the NodeMCU board with the Blynk Iot Platform to control a strip of RGB LEDs in an art project. Blynk is an IoT platform to connect your devices to the cloud, design apps to control them, analyze telemetry data, and manage these deployed products at scale.