Help Understanding Template Hierarchy

Question

I must be thick, but I could use some help grasping the way template files are chosen to be used. I noticed loop.php is no longer around, and looking at the file structure for twentytwelve there is now a 'page-templates' directory. As well as content-* files. We have index.php, page.php, content.php which one is used when? I know index.php is the "last resort" choice, however does content or page come first? And what is the difference between them? Thank you.

Answer 1

Template hierarchy consist of templates, but not every template file is necessarily in hierarchy.

Essentially hierarchy determines entry points (one of matching templates with pre-defined name structure), but from there template can further load additional arbitrary files.

page-templates directory holds custom templates for pages (is_page() branch in hierarchy). It's recent development that they can now reside in sub-folder.

content-*.php templates are called by Twenty Twelve like this from other templates: get_template_part( 'content', get_post_format() );. They are named arbitrarily and not part of template hierarchy - just a code organization choice that developers of this specific theme made.