This example is to configure the ESP8266 using nodeMCU firmware by the web page in AP mode. It allows you to configure and update the WiFi credentials, like SSID and password, using your browser on the smartphone or PC.
To use this firmware you will need the ESP8266 running the nodeMCU firmware.
http://pedrominatel.com.br/esp8266/wifi-web-setup-para-esp8266-com-nodemcu/