How to Create Custom Meta box in Wordpress

To create a Custom Meta box in wordpress follow below steps

Step1: Add this to your theme "functions.php"

<?php

define('MY_WORDPRESS_FOLDER',$_SERVER['DOCUMENT_ROOT']);
define('MY_THEME_FOLDER',str_replace('\\','/',dirname(__FILE__)));
define('MY_THEME_PATH','/' . substr(MY_THEME_FOLDER,stripos(MY_THEME_FOLDER,'wp-content')));

add_action('admin_init','my_meta_init');

function my_meta_init()
{
wp_enqueue_style('my_meta_css', MY_THEME_PATH . '/custom/meta.css');

foreach (array('post','page') as $type)
{
add_meta_box('my_all_meta', 'My Custom Meta Box', 'my_meta_setup', $type, 'normal', 'high');
}

add_action('save_post','my_meta_save');
}

function my_meta_setup()
{
global $post;

$meta = get_post_meta($post->ID,'_my_meta',TRUE);

include(MY_THEME_FOLDER . '/custom/meta.php');

echo '<input type="hidden" name="my_meta_noncename" value="' . wp_create_nonce(__FILE__) . '" />';
}

function my_meta_save($post_id)
{
if (!wp_verify_nonce($_POST['my_meta_noncename'],__FILE__)) return $post_id;

if ($_POST['post_type'] == 'page')
{
if (!current_user_can('edit_page', $post_id)) return $post_id;
}
else
{
if (!current_user_can('edit_post', $post_id)) return $post_id;
}

$current_data = get_post_meta($post_id, '_my_meta', TRUE);

$new_data = $_POST['_my_meta'];

my_meta_clean($new_data);

if ($current_data)
{
if (is_null($new_data)) delete_post_meta($post_id,'_my_meta');
else update_post_meta($post_id,'_my_meta',$new_data);
}
elseif (!is_null($new_data))
{
add_post_meta($post_id,'_my_meta',$new_data,TRUE);
}

return $post_id;
}

function my_meta_clean(&$arr)
{
if (is_array($arr))
{
foreach ($arr as $i => $v)
{
if (is_array($arr[$i]))
{
my_meta_clean($arr[$i]);

if (!count($arr[$i]))
{
unset($arr[$i]);
}
}
else
{
if (trim($arr[$i]) == '')
{
unset($arr[$i]);
}
}
}

if (!count($arr))
{
$arr = NULL;
}
}
}

?>