title: when I try to open an HTML file through `http://localhost/xampp/htdocs/index.html` it says unable to connect to localhost
body: <p>I have installed XAMPP , there is a  <code>htdocs</code> folder and inside it  <code>index.html</code> file , 
  when I try to open it in my browser through <code>http://localhost/xampp/htdocs/index.html</code> it says
  unable to connect to localhost .</p>
  
  <p>what is wrong ?</p>