Draw a diagram that demonstrates the path that a custom theme, which is a subtheme of Classy, traces back to the HTML output from Drupal core.

What is Stable? And why does it exist?

-> Stable is core theme of drupal, custom theme will use it as base theme.

-> It exists because it has base and stable structure. Without use it, the custom theme may broken when drupal core updated.

Find some commonly used base themes on Drupal.org and explain their use cases and when you might choose to extend them.

If you've already got a custom theme for your site, are there any benefits you might gain from refactoring it so that some parts of it become a base theme?