WP Custom Data is a WordPress widget which adds custom fields in your WordPress site. The custom fields can be simply usable in every section of your theme or in every plugin. For example if you want to add your address to the footer but the theme has not got an address field, you can simply install the WP Custom Data, enable the plugin, go in the widget section, add the WP Custom Data in any section (no matter where), write the address in one or more rows and save. Now WordPress knows your address and you can use this fields wherever you want. Do you want to use it in the footer? Open footer.php and write the PHP code:
$list = get_option('wp-custom-data');
where you want then, to display the address (the custom fields), use
echo $list['rowX'];
where X is the number of the row in the WP Custom Data where you have written the address.