Full Site Editing (FSE) is the WordPress approach to editing every part of a site — not just post content but headers, footers, archive pages, and single post templates — using the block editor. It replaces the traditional PHP template file system for themes that opt into it. Here is a practical overview for WordPress users who have not yet worked with FSE.
FSE vs Classic Themes: The Key Difference
Classic themes (Astra, Kadence, GeneratePress) use PHP template files to render headers, footers, and page structures. You customise them through the Customiser and child theme template overrides. Block themes use HTML template files that contain block markup, edited entirely through the Site Editor in the WordPress admin.
The Gutenberg plugin previews upcoming FSE features before they reach WordPress core. If you are on a classic theme, FSE features are limited. The full Site Editor experience requires a block theme.
Accessing the Site Editor
On WordPress 6.0 and above, go to Appearance, then Editor to open the Site Editor. If you see Customise instead of Editor, you are using a classic theme. Install a block theme like Twenty Twenty-Four or Kadence to access the full Site Editor.
Templates and Template Parts
In the Site Editor, Templates are full page layouts — Single Post, Archive, Front Page, 404, and so on. Template Parts are reusable sections — typically Header and Footer — that are shared across multiple templates.
To edit the site header, go to the Site Editor, then Template Parts, then Header. Changes here update the header across all templates that use it. This replaces editing header.php in classic themes.
Editing a Page Template
When editing a page in the block editor, click the Template name in the right sidebar (under Summary). This opens the template for that page type in the Site Editor. You can modify the template — adding or removing blocks, changing layout — and the changes apply to all pages using that template.
To create a custom template for a specific page, go to the Site Editor, then Templates, then Add New. Give the template a name. You can then assign this template to specific pages through the page editor sidebar.
Styles (Global Styles)
Global Styles in the Site Editor (the half-circle icon in the top right) replaces much of what the Customiser did for typography and colours. Set your body font, heading fonts, base colours, button styles, and link colours here. These apply globally and are stored in theme.json or as user style overrides.
What Does Not Change With FSE
Post content editing works the same way — the block editor for posts and pages is unchanged. Plugin functionality, WooCommerce, custom post types, and everything else continues to work the same way. FSE only changes how the template layer (header, footer, archive layouts) is built and edited.
Should You Switch to FSE?
If you are building a new site and are comfortable with the block editor, a block theme with FSE gives you a more integrated editing experience. If you have a well-configured existing site on a classic theme, there is no urgent reason to switch — classic themes continue to work and receive updates. The main reason to switch is if you want to edit templates and theme structure through the admin UI rather than through PHP files and the Customiser.
For custom block theme development including custom theme.json configuration, template design, and block pattern libraries, a WordPress developer can build a fully customised FSE-based site.