Magento : Add JavaScript / CSS

There is Two way for add external Javascript in magento

1) Using Page.xml
2) Using Head.phtml


1) Using Page.xml :::\\//

<action method="addJs"><script>directoryname/javascript_name.js</script></action>


2) Using Head.phtml :::\\//

<script type="text/javascript" src="<?php echo $this->getSkinUrl('directoryname/javascript_name.js') ?>"></script>

<link href='<?php echo $this->getSkinUrl('directoryname/css_name.css')  ?>' rel='stylesheet' type='text/css' />