Custom fields are extra pieces of structured information attached to a page or post in a content management system, stored separately from the main body text. In WordPress, a custom field might hold a property’s price, a clinic’s phone number, a course start date or the author of a quote, each in its own labelled box.
How custom fields work
WordPress stores the main content of a page in one place and keeps additional details as “post meta”: pairs of a key (the field name, such as event_date) and a value (such as 14 March 2027). The theme then pulls each value into the right spot on the page template. Because the data is labelled, the same field can appear on the page, in a listing, in a filter and in structured data, all from one entry.
WordPress has a basic custom fields panel built in, but most sites use a plugin to create friendlier editing screens with date pickers, image selectors, repeating rows and drop-down lists. Advanced Custom Fields (ACF) is the best known. At the time of writing (October 2026), there are two branches of it after a 2024 dispute between WP Engine and WordPress.org: ACF from WP Engine, and a fork called Secure Custom Fields in the WordPress.org directory. If your site relies on either, know which one you have and where its updates come from.
Custom fields usually pair with a custom post type. A recruitment firm might have a “Jobs” post type with fields for salary, location, contract type and closing date, so every job page follows the same structure without anyone formatting it by hand.
Why they matter
Structured fields keep content consistent. Instead of fifteen editors typing a price fifteen different ways, there is one box with one format. That consistency matters for search in a practical way: values stored in fields can be output as schema markup automatically, so a job listing, an event or a product carries correct structured data on every page rather than on the few someone remembered to mark up.
Fields also make the site easier to change later. If a UK estate agent wants to show council tax band on every listing, adding one field and one line to the template is far simpler than editing hundreds of pages. And when a site moves to a new theme or platform, cleanly labelled data migrates; information buried inside page builder layouts often does not.
Common mistakes
- Important text that search engines cannot see. If a field’s value is only used in a hidden tab loaded by JavaScript after a click, or not output on the page at all, it adds nothing to how the page ranks.
- Thin pages built from fields alone. A template that outputs ten short fields and no written explanation produces hundreds of near-identical pages.
- Field sprawl. Years of additions leave dozens of unused fields, which slow down the editing screen and clutter the database.
- Fields defined only in the database. Field groups that exist only in wp-admin, rather than in code or exported JSON, are easy to lose during a rebuild.
- Theme lock-in. If the template code that displays fields lives inside the theme, switching theme makes the information vanish from the front end.
How to act on it
List the information that repeats across your key page types: services, locations, team members, products, events. Anything that follows the same pattern every time is a candidate for a field. Check that every field that matters to a customer actually renders as visible text in the page source, and that the values feeding structured data are filled in on every page.
Export field definitions into version control or a JSON file so they survive a rebuild, and delete fields nobody uses. If you are planning templates for a new WordPress build, or untangling an existing one, I cover field and template design as part of WordPress SEO.