ESP8266 is one of the most popular WiFi Modules because of this device we can connect WiFi and communicate with other actuators and sensors.
It is also called ESP8266 NodeMCU, there are different versions ESP8266 NodeMCU 0.9 is ESP-12 Module and NodeMCU 1.0 is ESP-12E Module.
This is just a testing program of your NodeMCU or ESP8266 WiFi Module, so you can test your device Step-by-Step.
Step 1: Install Arduino IDE and Setup ESP8266 Library
Step 2: Connect ESP8266 to PC and Open Blink Program
Goto File and Example, select ESP8266 and click on blink program
Step 3: Upload Program