Let me explain you by examples which is more easy to understad.
If
register_global is off the your code would be like this:
Code:
<form method="post" action=".">
<input type="text" name="userName">
<input type="submit">
</form>
<?php
$userName = $_REQUEST['userName'];
print $userName;
?>
But with
register_global turned on you can do like this:
Code:
<form method="post" action=".">
<input type="text" name="userName">
<input type="submit">
</form>
<?php
print $userName;
?>
From siLenTz
Hope you are understand....