How can I list tags arranged by groups?

You could use the tag_groups_cloud function and set the second parameter to “true”, try for example:

if ( function_exists( 'tag_groups_cloud' ) ) print_r( tag_groups_cloud( array( 'orderby' => 'count', 'order' => 'DESC' ), true ) );

That’s awesome!

Thank you very much!

You are welcome!