Restricted access error in Joomla

'Restricted access' error in Joomla

When you work in Joomla, you can get the most common error 'Restricted access' error.
There many possibilities that show this error, but the most common mistake is to write incorrect statement.
you can write:
define('JEXEC') or die ('Restricted access');

but the corrected format is :
defined('JEXEC') or die ('Restricted access');  and run the page.
and Wow!!! you can get the same error message. now this is the time to more correct format is:
defined('_JEXEC') or die('Restricted access');

now run the page , you will not get the error.