$ is not defined in wordpress code example

Example 1: $ is not defined

<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js" type="text/javascript"></script>

Example 2: jquery is not defined error in wordpress

/** Absolute path to the WordPress directory. */

if ( !defined('ABSPATH') )

define('ABSPATH', dirname(__FILE__) . '/');

define('CONCATENATE_SCRIPTS', false);