WordPress Multisite allows users to have multiple sites in a single installation of the WordPress application. The multisite network owner can manage multiple sites from the same WordPress admin panel, including the number of sites, what themes and plugins are active for different websites, users, and website features separately.

WordPress Multisite is best used when you are creating a network of websites that share similar aspects and functionality. This is because all plugins and themes are shared between websites and you can configure everything globally for all websites at the same time. If you plan to have websites with different themes or allow users to manage the theme and plugins of their own websites, WordPress Multisite is not recommended.