Multisite is a type of WordPress installation that allows you to create and manage a network of multiple websites from a single WordPress dashboard. This lets you easily make changes and keep all of your websites updated from one place.
You can create a multisite network for yourself that only you have access to. Or you could add other users who can create their own sites inside your network, and limit them from accessing more powerful WordPress features.
For example, Harvard University has a WordPress multisite network called Harvard Blogs that allows anyone with a harvard.edu email address to create their own blog. Bloggers can publish blog posts on their own sites, but only the owner of the multisite, called the “super admin”, can install plugins or make other sitewide changes.