The Twenty Themes

The bundled Twenty themes exist to demonstrate what WordPress can do that year, not to be a starter kit. That is why they are plain, why each one is abandoned as a design the following year, and why they remain the most reliable code in your themes directory.

The series has two distinct eras, and the boundary is Twenty Twenty-Two.

The classic era: Twenty Eleven through Twenty Twenty-One

These are PHP themes. Templates are .php files, styling is a stylesheet, and site-wide settings live in the customiser. They pre-date the block editor's control of layout, and most pre-date it entirely.

They are still installed on many sites for one good reason: they are the fallback. If a theme fatally errors, WordPress will switch to a bundled default so the site stays up rather than showing a white screen. That safety net is worth one theme's disk space.

What they are not is a base for a new site in a modern workflow. Building on Twenty Sixteen today means writing PHP templates for a site whose editor expects blocks, and fighting the mismatch every time content is added.

The block era: Twenty Twenty-Two onward

Twenty Twenty-Two was the first default theme with no PHP templates at all. The change is structural rather than cosmetic:

This is why the customiser appears to vanish when you activate a modern default theme. Nothing is broken — the settings moved into the site editor, and what a block theme is explains the new locations. If the editor itself will not open, that is a separate problem: site editor not loading.

The theme.json file is the piece worth understanding even if you never build a theme. It defines the palette, type scale and spacing steps available to editors, which is how a block theme keeps a site consistent without policing the people writing it.

Are they any good as a site base?

Honestly, better than their reputation.

In favour: maintained by WordPress itself, so no vendor can abandon them; light, with no page builder or demo importer; accessible, having been reviewed against the project's own standards; and a genuinely good demonstration of the styling system, which makes them easy to learn from.

Against: designed as a showcase for one release, so the aesthetic is deliberately neutral; sparse pattern libraries compared with commercial themes; no support beyond community forums; and every new WordPress version brings a new default, so yours stops being the current example.

That last point matters less than it sounds. A default theme is not deprecated when the next one ships — it continues to receive security and compatibility updates. But its design will look like the year it was released, which is the same trade every theme makes and only the Twenty series makes openly.

The practical route is a child theme or, on a block theme, style variations and the site editor's own customisations — see customising a theme for which changes survive updates.

Choosing between a default and something else

If you are moving from a classic theme to a block one, the transition is bigger than a normal theme switch — widgets, menus and customiser settings do not carry across cleanly. Changing a WordPress theme covers the checklist, and doing it on a staging copy rather than live is the difference between an afternoon and an incident.

Housekeeping

• Keep exactly one unused default as the fallback, and keep it updated.
• Delete the rest. An inactive theme is still code on the server that needs patching, a point made in the security checklist.
• Never edit a default theme directly. It updates with WordPress, and your changes go with it.
• Check which one is your fallback before assuming — it is normally the newest bundled theme still installed.

Common mistakes

• Deleting every default, leaving no fallback when the active theme fatals.
• Building a new site on a classic-era default and writing PHP templates against a block editor.
• Assuming the customiser was removed by a plugin after activating a block theme.
• Editing theme files directly and losing the work at the next core update.
• Judging the whole series by Twenty Seventeen, which is nearly a decade of block editor development ago.

Verify

Activate a block-era default on a staging copy and open the site editor: you should be able to edit the header, footer and templates without touching a file. Check that your live site still has one unused default installed as a fallback. Then confirm nothing on the site depends on a theme you were about to delete — orphaned widgets and menu assignments are the usual surprise, and creating a menu is where you will be rebuilding them.