Can someone give other examples of this? Like an example of a script name to be put in the SERVER code or at least a scenario of where and when to use this code? Thank you.

Answer 1

if you install a wordpress in your localhost before to publish it, you can change the database config depending on $_SERVER['HTTP_HOST'].
So you can work in your localhost and in PRO with the same config.php.
Google it fot mote info.