Just as you might imagine, “Multisite” is a portmanteau of the words “multiple” and “websites.” In WordPress, multisite refers to the ability for one installation of WordPress to operate multiple, different websites.
Multisite functionality has been a part of WordPress since version 3.0. It allows an administrator to operate wholly different websites from one installation of WordPress and/or manage subdomains and subdirectories of one website.
In order to activate Multisite functionality, you’ll need first disable all active plugins. Next, edit the wp-config.php file and add this line right before the line that says “That’s all, stop editing! Happy blogging”:
/* Multisite */ define('WP_ALLOW_MULTISITE', true);
Once that’s done, you can now activate Multisite by logging into the administration area of your website. Click on “Tools” and then “Network Setup.” From there, you can choose whether the new websites will be classified as a subdomain or a subdirectory.
You’ll then be prompted to give your new network a name and login information for the administrator. After that, click on “Install.” Once that is completed, you’ll need to make additional changes to your “.htaccess” and “wp-config.php” files.
Note: WordPress websites hosted by WordPress.com cannot activate Multisite functionality.
Once everything is working, you’ll see a new option appear in the left-hand column of your administration screen called “Sites.” This will allow you to manage the different websites that have been added to your network. For more information on setting up and running a network of WordPress websites using Multisite, click here.
Note: Only a user with Super Admin status can make simultaneous changes to all networked sites, including changing the theme. Super Admins are also the only users who can see archived websites that were previously part of your network.