ใครพออธิบายโด้คนี้ได้บ้าง ไม่เก่งเรื่องโด้ค ขอบคุณ

#include <ESP8266WiFi.h>
#include <ESP8266WebServer.h>

const char* ssid = "WIFI_SSID";
const char* password = "WIFI_PASSWORD";

const IPAddress ip(192, 168, 1, 100);
const IPAddress subnet(255, 255, 255, 0);
const IPAddress gt(192, 168, 1, 1);

const int SwitchPin = 12; // GPIO12
int SwitchValue = HIGH;

ESP8266WebServer server(80);

void handleNotFound(){
  //server.send(404, "text/plain", "404 Not Found");

  if(SwitchValue == HIGH) {
    server.send(200, "text/plain", "ON");
  }else{
    server.send(200, "text/plain", "OFF");
  }

  delay(1000);
}

void setup(void){

  // Set Output PIN
  pinMode(SwitchPin, OUTPUT);
  digitalWrite(SwitchPin, SwitchValue);

  // Connect WiFi
  WiFi.mode(WIFI_STA);
  WiFi.config(ip, gt, subnet);
  WiFi.begin(ssid, password);

  // Wait for connection
  while(WiFi.status() != WL_CONNECTED){
    delay(1000);
  }

  server.on("/", [](){
    if(SwitchValue == HIGH) {
      server.send(200, "text/plain", "ON");
    }else{
      server.send(200, "text/plain", "OFF");
    }

    delay(1000);
  });

  server.on("/ON", [](){
    SwitchValue = HIGH;

    server.send(200, "text/plain", "ON");
    digitalWrite(SwitchPin, SwitchValue);
    delay(1000);
  });

  server.on("/OFF", [](){
    SwitchValue = LOW;

    server.send(200, "text/plain", "OFF");
    digitalWrite(SwitchPin, SwitchValue);
    delay(1000);
  });

  server.onNotFound(handleNotFound);

  server.begin();
}

void loop(void){
  server.handleClient();
}