WordPress 4.3 Changes in Template Hierarchy

In WordPress  4.3 there is a new template file added in theme template hierarchy called singular.php . This will allow theme authors to use a common template for any singular post type.

It follows the rules of is_singular() and comes after single-{post-type}.php, single-post.php, single.php, andpage.php.

To learn more about WordPress theme template heirarchy : https://developer.wordpress.org/themes/basics/template-hierarchy/