An associative array stores an arbitrary index in addition to the values. This is useful for storing configuration information such as in the $_SERVER array.

An individual element of this array can be retrieved with the following:

$_SERVER['SITE_HTMLROOT']

To loop through all of the elements in $_SERVER and display the values and their corresponding indexes, use the following:

foreach ( $_SERVER as $ind=>$val )
echo "$ind : $val
";