what is exaclty raw POST data?
$_POST can be said as and outcome after splitting the $HTTP_RAW_POST_DATA, php splits the raw post data and formats in the way we see it in the $_POST For example:
$HTTP_RAW_POST_DATA looks something like this
then $_POST would look like this:
$_POST = array(
"key1" => "value1",
"key2" => "value2",);