- WordPress Multisite meaning in plain English
- How a Multisite network is built behind the scenes
- Subdomain or subdirectory Multisite addresses
- Who looks after a Multisite network: the super admin
- How plugins and themes behave on a Multisite network
- When WordPress Multisite makes sense, and when it doesn't
- Before you create a Multisite network
- Sharing your WordPress knowledge with other developers
- Frequently asked questions
WordPress Multisite is a built-in feature that lets you run several WordPress sites from one installation. The sites form a network that shares the WordPress core files and can share plugins and themes, while each site keeps its own content and database tables. A super admin manages the network.
Running two or three WordPress sites usually means two or three logins, two or three sets of updates and a lot of switching tabs. Multisite is WordPress's built-in answer to that, but it isn't the right answer for every project, and it's worth knowing what it really does before you switch it on.
I've pulled this together from the WordPress developer documentation on Multisite. It's written for site owners and anyone new to WordPress development, with no code needed to follow along.
WordPress Multisite meaning in plain English
WordPress Multisite is a feature that lets you run several WordPress sites from one installation. The developer documentation calls the group a network: a collection of sites that share one WordPress installation, including its core files, and that can share plugins and themes.
Think of it as a block of flats. There's one building, with one set of foundations and one landlord looking after the shared parts. Each flat has its own front door and its own furniture. In Multisite, the building is the WordPress install, and each flat is a separate site with its own content.
The documentation gives a typical use: a business with regional sites that share resources such as themes and plugins but keep different content for each region.
How a Multisite network is built behind the scenes
Under the bonnet, a network shares less than you might expect. According to the documentation, each site has its own database tables and its own media upload directory, but it doesn't get a separate folder on the server for the WordPress files. The users table is the one that's shared across the whole network.
- Shared: the WordPress core files, the plugin and theme files and the list of users.
- Separate for each site: posts, pages, settings, comments and uploaded media.
- Needed to run it: URL rewrites must be enabled on the server.
Because users live in a shared table, someone can have one account for the whole network. They still need a role on a specific site before they can get into it.
Subdomain or subdirectory Multisite addresses
When you create a network you choose how the sites' web addresses are laid out. There are two options, and the documentation notes that you can switch later but warns that reconfiguring may not be easy, so it's worth deciding carefully at the start.
| Setup | How the addresses look | Good to know |
|---|---|---|
| Subdirectory | Sites sit in paths on one domain, like example.com/shop | Path-based; no extra DNS setup |
| Subdomain | Each site gets its own prefix, like shop.example.com | Domain-based; wildcard DNS is needed for on-demand sites |
| Mapped domains | A site can use a completely separate domain name | Covered in a separate guide in the documentation |
The wildcard DNS note is the technical bit. DNS is the system that translates domain names into server addresses, and I've explained it in what the domain name system does if you'd like the background.
Who looks after a Multisite network: the super admin
The person who installs the network becomes its super admin, also called the Network Admin. The documentation says the Network Admin is the role that can carry out restricted tasks, such as installing themes and plugins, and can reach the plugins of every site.
Ordinary site admins have less power. They can't install new themes or plugins, and they can't edit the profiles of users on their site. If the Network Admin turns on the Plugins page for them under the network settings, they can switch on or off plugins that haven't been network activated. Network-activated plugins show up to them as Network Active, with no option to deactivate.
You also decide who can create sites. Users can create their own sites on demand, much like blogs on WordPress.com, or you can keep site creation to yourself.
How plugins and themes behave on a Multisite network
This is where Multisite catches people out, so it's worth reading slowly:
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- Plugins are installed from the network dashboard. A plugin can be site activated, so it loads only on one site, or network activated, so it runs on every site.
- Must-use plugins in the mu-plugins folder run on all sites, can't be deactivated and are hidden from per-site plugin lists.
- Not every plugin works on Multisite, so check each one before you install it.
- Themes are installed network-wide, so editing a theme changes it for every site using it.
- Network activating a theme only makes it available; a site still has to have it enabled.
That last point on editing is the reason many people create a child theme before customising. If you're weighing that up, my explainer on what a WordPress child theme is covers it.
When WordPress Multisite makes sense, and when it doesn't
Multisite suits situations where the sites are closely related and one person or team looks after all of them. Typical examples from the documentation's description are regional versions of one business, or a network where members can create their own sites.
It suits less well when the sites are unrelated, when each needs very different plugins or when different people need full control of their own site. Sites on a network share one installation, so a problem with a shared plugin or the server can affect all of them. Separate installs keep things isolated in return for more admin work.
Before you create a Multisite network
The documentation lists some sensible steps if you're converting an existing site:
- Back up your database and files, unless it's a fresh install with nothing to lose.
- Check that pretty permalinks work on your current single-site install.
- Deactivate all active plugins. You can reactivate them after the network is created.
- If you plan to run WordPress from its own directory, do that before enabling Multisite.
- Enable Multisite by adding the allow line to the wp-config.php file, then follow the installer's instructions, which include adding further lines to wp-config.php and .htaccess. Back up both files first.
Your existing site is updated when you create a network, so take the backup seriously. You might also need to log in again and clear your browser cache and cookies afterwards.
Sharing your WordPress knowledge with other developers
Multisite is a topic where people value plain explanations, because the documentation is technical. If you work with it regularly, there's an audience for what you've learned.
WordPress developers can find WordPress blogs that accept contributor articles on this page.
Frequently asked questions
Is WordPress Multisite built into WordPress?
Yes. It's a feature of WordPress itself, switched on by adding a setting to the wp-config.php file. The documentation says the server needs URL rewrites enabled.
Do all sites in a network share one database?
Each site has its own database tables. According to the documentation, the users table is the only one shared across the network.
Can I use any plugin on Multisite?
Not necessarily. The documentation says not every plugin works on Multisite, so check each plugin before installing it.
Can I change from subdirectories to subdomains later?
The documentation says you can switch, but that reconfiguring may not be easy. It's better to decide at the start.
Who can install plugins and themes on a network?
The super admin, also called the Network Admin. Ordinary site admins can't install new themes or plugins.
