$_SERVER['CI_ENV'] -- where is and ENVIRONMENT this set?

I followed some examples and I tried to set it in .htaccess with some ifs depending on the url e.g. if it's localhost then set Development etc, and then setting it like this in index.php:

Code:

define('ENVIRONMENT', isset($_SERVER['CI_ENV']) ? $_SERVER['CI_ENV'] : 'development');

But it only worked on my localhost and not on my server. So I just hard coded in the index.php:

Code:

define('ENVIRONMENT', 'production');

Do the one thing you think you cannot do. Fail at it. Try again. Do better the second time. The only people who never tumble are those who never mount the high wire.