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Full Site Editing (FSE)

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In brief · quick answer

Full Site Editing (FSE) is a set of WordPress features that extends the block editor (Gutenberg) from editing page content to editing the entire site. With FSE and a block theme, you can customize headers, footers, templates, and global styles using the visual Site Editor, all without touching code.

§ 1 Definition

Full Site Editing (FSE) is a paradigm shift in WordPress theming that extends the Gutenberg Editor's block-based approach from page content to the entire site. Launched in WordPress 5.9 (January 2022) and refined through subsequent releases, FSE lets users edit every part of their website through a unified visual interface. With FSE, there's no separate header.php, footer.php, or sidebar.php. Instead, you use block themes where all template parts are composed of Gutenberg blocks. The Site Editor provides a visual canvas for editing templates (like single post, archive, 404) and template parts (like header, footer, sidebar). Global Styles controls typography, colors, and layout settings across the entire site. FSE represents the most significant change to WordPress theming since the introduction of the Template Hierarchy. It's not optional. WordPress core development is focused on FSE, and classic themes (while still supported) are effectively in maintenance mode.

§ 2 Core FSE Components

FSE comprises several interconnected features: Block Themes: The foundation of FSE. Block themes use `.html` template files with block markup instead of `.php` template files. A block theme needs at minimum `templates/index.html` and `styles/theme.json`. Template files go in `/templates/`, template parts (reusable components like headers and footers) go in `/parts/`. Site Editor: The visual interface for editing templates and template parts. Accessed via Appearance > Editor. It shows a full-site preview where you can click on any element to edit it. Equivalent to a visual page builder for the entire site, but built into WordPress core. Template Editor: Within the Site Editor, you can create, modify, and assign templates. Want your blog archive to have a two-column layout with a sidebar while your case study archive is full-width? Create separate templates through the visual editor. Global Styles: A centralized style system controlled via `theme.json` and the Styles interface in the Site Editor. You can set typography (font families, sizes, line heights), colors (palettes, gradients, duotone), and layout settings (content width, spacing) that apply site-wide. Changes update everywhere instantly. Block Patterns: Pre-designed groups of blocks that can be inserted as a unit. FSE templates rely heavily on patterns for common layouts (hero sections, feature grids, call-to-action blocks). The Pattern Directory provides thousands of free patterns.

§ 3 FSE vs Classic Themes

The shift from classic to block themes represents a fundamental architectural change: Classic themes (PHP-based): - Template files are PHP (header.php, single.php, archive.php) - Design changes require PHP, CSS, and template tag knowledge - Customizations often need a child theme or direct file editing - Content and design are managed in separate systems Block themes (FSE): - Template files are HTML with block markup (`templates/single.html`) - Design changes happen through the visual Site Editor - No child theme needed for most customizations (the Site Editor saves changes to the database) - Content and design are managed through the same block interface The practical difference: a non-technical content editor can use FSE to add a new section to the site footer or change the header layout without submitting a developer ticket. With classic themes, the same change requires a developer to edit PHP files, deploy the update, and test it. FSE doesn't eliminate the need for developers. Building a block theme, creating custom blocks, and configuring `theme.json` requires development skills. But it shifts routine design tasks from developers to content editors.

§ 4 When to Use FSE (and When Not To)

FSE is production-ready for many sites but has limitations: Use FSE when: - Building a new site from scratch with a block theme - Your content team needs to make site-wide design changes independently - You want a single consistent editing experience (content + design in one tool) - Your site has standard layouts (blog, brochure, portfolio) Avoid FSE when: - Maintaining an existing site with a classic theme. The migration cost rarely justifies the benefits. - Your site relies heavily on a page builder (Elementor, Divi). FSE doesn't integrate with page builder content. - You need pixel-perfect, asymmetrical layouts. FSE's block constraints make avant-garde design difficult. - Your team has no React/block development experience. Custom block development is required for advanced functionality. For most new WordPress projects in 2025, starting with a block theme and FSE is the right call. For existing sites, FSE adoption is a project, not an upgrade. The transition path usually involves building a new block theme alongside the existing classic theme, migrating content, and switching themes when ready.

§ 5 Common questions

Q. Is Full Site Editing stable enough for production?: A. Yes. FSE has been production-ready since WordPress 6.0+ (2022). Major sites run on FSE. Minor gaps exist (custom user role support, some advanced query features) but it's suitable for most projects.
Q. Do I lose FSE changes when I update my theme?: A. No. Changes made through the Site Editor are saved to the WordPress database and are independent of the theme's template files. They persist across theme updates.
Q. Can I use FSE with my existing classic theme?: A. No. FSE requires a block theme. You can convert a classic theme to a block theme, but it's essentially rebuilding the theme from scratch.

Key takeaways

Full Site Editing extends the Gutenberg block editor to headers, footers, templates, and global styles.
FSE requires block themes (.html template files + theme.json) instead of classic PHP template files.
Non-technical editors can make site-wide design changes through the visual Site Editor.
FSE is the future of WordPress theming. New projects should start with block themes. Existing sites should evaluate migration costs carefully.

How Atomic Glue helps

We build custom block themes with Full Site Editing for clients who want modern WordPress without page builder bloat. Custom blocks, theme.json configuration, and content editor training included. Get in touch about your WordPress build.

Get in touch

# Full Site Editing (FSE)

Category: Cms (also: Design)

Author: Atomic Glue Editorial Team

## Definition

Full Site Editing (FSE) is a paradigm shift in [WordPress](/glossary/wordpress) theming that extends the [Gutenberg Editor's](/glossary/gutenberg-editor) block-based approach from page content to the entire site. Launched in WordPress 5.9 (January 2022) and refined through subsequent releases, FSE lets users edit every part of their website through a unified visual interface. With FSE, there's no separate header.php, footer.php, or sidebar.php. Instead, you use block themes where all template parts are composed of [Gutenberg](/glossary/gutenberg-editor) blocks. The Site Editor provides a visual canvas for editing templates (like single post, archive, 404) and template parts (like header, footer, sidebar). Global Styles controls typography, colors, and layout settings across the entire site. FSE represents the most significant change to WordPress theming since the introduction of the Template Hierarchy. It's not optional. WordPress core development is focused on FSE, and classic themes (while still supported) are effectively in maintenance mode.

## Core FSE Components

FSE comprises several interconnected features: **Block Themes:** The foundation of FSE. Block themes use `.html` template files with block markup instead of `.php` template files. A block theme needs at minimum `templates/index.html` and `styles/theme.json`. Template files go in `/templates/`, template parts (reusable components like headers and footers) go in `/parts/`. **Site Editor:** The visual interface for editing templates and template parts. Accessed via Appearance > Editor. It shows a full-site preview where you can click on any element to edit it. Equivalent to a visual page builder for the entire site, but built into WordPress core. **Template Editor:** Within the Site Editor, you can create, modify, and assign templates. Want your blog archive to have a two-column layout with a sidebar while your case study archive is full-width? Create separate templates through the visual editor. **Global Styles:** A centralized style system controlled via `theme.json` and the Styles interface in the Site Editor. You can set typography (font families, sizes, line heights), colors (palettes, gradients, duotone), and layout settings (content width, spacing) that apply site-wide. Changes update everywhere instantly. **Block Patterns:** Pre-designed groups of blocks that can be inserted as a unit. FSE templates rely heavily on patterns for common layouts (hero sections, feature grids, call-to-action blocks). The Pattern Directory provides thousands of free patterns.

## FSE vs Classic Themes

The shift from classic to block themes represents a fundamental architectural change: **Classic themes (PHP-based):** - Template files are PHP (header.php, single.php, archive.php) - Design changes require PHP, CSS, and template tag knowledge - Customizations often need a child theme or direct file editing - Content and design are managed in separate systems **Block themes (FSE):** - Template files are HTML with block markup (`templates/single.html`) - Design changes happen through the visual Site Editor - No child theme needed for most customizations (the Site Editor saves changes to the database) - Content and design are managed through the same block interface The practical difference: a non-technical content editor can use FSE to add a new section to the site footer or change the header layout without submitting a developer ticket. With classic themes, the same change requires a developer to edit PHP files, deploy the update, and test it. FSE doesn't eliminate the need for developers. Building a block theme, creating custom blocks, and configuring `theme.json` requires development skills. But it shifts routine design tasks from developers to content editors.

## When to Use FSE (and When Not To)

FSE is production-ready for many sites but has limitations: **Use FSE when:** - Building a new site from scratch with a block theme - Your content team needs to make site-wide design changes independently - You want a single consistent editing experience (content + design in one tool) - Your site has standard layouts (blog, brochure, portfolio) **Avoid FSE when:** - Maintaining an existing site with a classic theme. The migration cost rarely justifies the benefits. - Your site relies heavily on a page builder (Elementor, Divi). FSE doesn't integrate with page builder content. - You need pixel-perfect, asymmetrical layouts. FSE's block constraints make avant-garde design difficult. - Your team has no React/block development experience. Custom block development is required for advanced functionality. For most new WordPress projects in 2025, starting with a block theme and FSE is the right call. For existing sites, FSE adoption is a project, not an upgrade. The transition path usually involves building a new block theme alongside the existing classic theme, migrating content, and switching themes when ready.

## Common questions

Q: Is Full Site Editing stable enough for production?

A: Yes. FSE has been production-ready since WordPress 6.0+ (2022). Major sites run on FSE. Minor gaps exist (custom user role support, some advanced query features) but it's suitable for most projects.

Q: Do I lose FSE changes when I update my theme?

A: No. Changes made through the Site Editor are saved to the WordPress database and are independent of the theme's template files. They persist across theme updates.

Q: Can I use FSE with my existing classic theme?

A: No. FSE requires a block theme. You can convert a classic theme to a block theme, but it's essentially rebuilding the theme from scratch.

## Key takeaways

Full Site Editing extends the Gutenberg block editor to headers, footers, templates, and global styles.
FSE requires block themes (.html template files + theme.json) instead of classic PHP template files.
Non-technical editors can make site-wide design changes through the visual Site Editor.
FSE is the future of WordPress theming. New projects should start with block themes. Existing sites should evaluate migration costs carefully.

## Related entries

Last updated July 2025. Permalink: atomicglue.co/glossary/full-site-editing-fse