Somebody built your website a few years ago, and now every question you ask seems to end with “that depends on the theme”. The header will not change the way you want, the fonts look dated, and a developer has quoted for a “theme update” without saying what that involves. It is hard to make good decisions about a part of the site nobody has explained to you.
So this page starts with a simple question, what is a WordPress theme, and then covers what it decides on your site, what it has nothing to do with, and how to find out which one you have. It is the theme section of our WordPress guide for business owners, and the other posts in this section go deeper into each job.
What is a WordPress theme, in plain terms
A theme is a set of files that tells WordPress how to present your content. Your pages, posts, images and settings live in the database. The theme takes that content and wraps it in a layout: where the header sits, how wide the text runs, what a blog post looks like, which fonts and colours are used unless you choose others.
Only one theme is active at a time. You can see it under Appearance → Themes, where the active one is listed first. The files sit in a folder inside wp-content/themes on your hosting account, next to any other themes that are installed but switched off.
A picture that helps: your content is the furniture and the theme is the room. Move to a different room and the furniture comes with you, but it may not fit against the new walls in quite the same way.
What your theme controls, and what it leaves alone
Owners often blame the theme for things it never touches, and miss the things it quietly owns. This split holds for most sites:
| Usually the theme’s job | Usually not the theme’s job |
|---|---|
| Header and footer layout | The words on your pages and posts |
| Default fonts, colours and spacing | Contact forms (a form plugin handles these) |
| Layouts for pages, posts, archives, search results and the 404 page | SEO titles and descriptions (an SEO plugin) |
| Blog list design and sidebars | Users, passwords and roles |
| How the menu behaves on a phone | Backups, security and email delivery |
| Extras some themes bundle: sliders, portfolios, shortcodes | Shops, bookings and payments (plugins such as WooCommerce) |
The last row on the left is the grey area. Large multipurpose themes often add their own features, such as a portfolio section, a testimonials type or a set of shortcodes. They feel like part of the website, but they belong to the theme, and they stop working if the theme is replaced. That is the main reason changing themes takes more care than people expect.
Block themes and classic themes
WordPress now has two kinds of theme, and they are edited in different places.
Block themes build everything out of blocks, the header and footer included. Recent default themes from WordPress itself, Twenty Twenty-Five among them, work this way. You edit them in the Site Editor at Appearance → Editor. Fonts, colours and spacing for the whole site live in the Styles panel there.
Classic themes, which include most older themes and many long-running popular ones, use Appearance → Customize for site-wide options, along with Appearance → Menus and Appearance → Widgets. What the Customizer offers depends entirely on the theme. One theme gives you dozens of panels; another gives you a logo field and little else.
How to tell which kind you have
- Log in and hover over Appearance in the left-hand menu.
- If you see Editor, and usually no Menus or Widgets, you are on a block theme.
- If you see Customize, normally with Menus and Widgets beside it, it is a classic theme.
A few themes mix the two, keeping the Customizer while using some block features, and a classic theme may also show a Design or Patterns item. Recent WordPress versions add Fonts to the Appearance menu for every theme, so that one tells you nothing. Editor versus Customize is the line to look for.
When a page builder sits on top of the theme
Many business sites are built with Elementor, Beaver Builder or a similar page builder. The split then changes. The builder designs the inside of each page, and sometimes the header and footer as well, while the theme supplies a light frame underneath. Some sites run a deliberately bare theme, such as Hello Elementor, for exactly this reason. Divi is both a theme and a builder, which makes the line harder to see.
If clicking Edit on a page opens a builder instead of the normal WordPress editor, changes to that page happen in the builder. Our walkthrough on editing a page in Elementor covers the basics for the most common one.
Finding out which theme your site uses
Inside WordPress, Appearance → Themes shows the active theme with its name and version. Click it for details. If it is a child theme, the details say which parent theme it depends on.
If you cannot log in yet, or you are curious about another site, our free WordPress theme detector reads the theme name from the public page. Then write down four things: the theme name, whether it was free or bought, who holds the licence, and whether a child theme is in use. That short note saves time in every conversation you will have with a developer.
Parent themes, child themes and updates
Themes receive updates just as plugins do: bug fixes, security patches and support for newer WordPress versions. An update replaces the theme’s files, and anything somebody typed into those files by hand is replaced with them.
Changes made through the Site Editor, the Customizer or a theme’s own options panel are saved in the database, so updates leave them alone. Hand-written code is different, and a child theme is the standard place for it. Whether your site needs one is covered in do you need a child theme, and the section has a separate post on the checks to make before pressing update.
If you came here wanting to adjust the look of the theme you already have, our step-by-step article on customising a WordPress theme safely is the place to start.
The rest of the theme section
Each of these takes one job and walks through it for block and classic themes:
- Switching to a new theme without losing content: what carries over, what needs redoing, and how to test first.
- Changing your fonts through the Font Library or the Customizer.
- Setting your brand colours across the site and on single blocks, with readable contrast.
- Adding small CSS tweaks in the right place, so they survive updates.
- Whether a paid theme is worth it compared with a free one.
- Judging a theme’s quality before you commit to it.
Frequently asked questions
Can a WordPress site use more than one theme at the same time?
No. Only one theme is active at a time. A child theme might look like an exception, but it works together with its parent as a single active theme. If different pages need different layouts, the answer is usually a different page template within the same theme, not a second theme.
Should I delete the themes I am not using?
Mostly, yes. Keep the active theme, its parent if you use a child theme, and one current default WordPress theme as a fallback for troubleshooting. Delete the rest. Inactive themes still sit on the server, still need updates, and an outdated one can carry a known security hole even while switched off.
Does my theme affect speed and search results?
It can. A heavy theme loads extra code on every page, which slows the site down, and a poorly built one may use headings or markup in odd ways. A theme will not make a site rank by itself, but a lean, well-maintained theme removes problems that hold good content back.
Who owns the theme licence if my developer bought it?
Whoever bought it, under whatever account was used. If your developer bought a premium theme in their own name, updates and support may be tied to their account. Ask for the licence to be moved to a business email address you control, or buy your own copy, so you are not stuck if you part ways.
Not every owner wants to dig through Appearance screens to work this out. Our WordPress support team can look at your site and tell you, in plain words, which theme it runs and what shape it is in.
All guides in this section
- How to Change Your WordPress Theme Without Losing Content
- WordPress Child Theme: Do You Need One, and How to Set It Up
- How to Change Fonts in WordPress (Block and Classic Themes)
- How to Change Colors in WordPress: Palette and Blocks
- WordPress Global Styles: Site-Wide Design in Block Themes
- How to Add Custom CSS in WordPress Without Losing It
- Free vs Premium WordPress Theme: Is a Paid Theme Worth It?
- How to Update a WordPress Theme Without Losing Changes
- How to Switch From Elementor to the Block Editor
- How to Edit an Elementor Page Without Breaking It
- How to Import a WordPress Theme Demo Safely
- How to Check the Quality of a WordPress Theme
- WordPress Design Mistakes Small Businesses Make
- How to Make a Custom 404 Page in WordPress
Next in this series: How to Change Your WordPress Theme Without Losing Content
