Sometimes you will want to hide your website, either because new content is not finished yet, you are re-launching it with new changes or for some other reason.    You can do this rather easily with Drupal.

After logging into your Administrative account, go to Configuration -> Development ->  Maintenance Mode

From here check the Put site into Maintenance mode checkbox and then Save your settings.  

When you are ready to re-enable the site, just uncheck the setting and save to make your changes live.