The multi-user (MU) feature has been rolled into core as Multisite ever since Version 3.0.
It is ideal for a central system administrator to set up a large network of blogs with one installation. (The sites in this network have separate URLs which forward to the subsites.)
Individual site administrators are able to securely manage their templates and settings without affecting the other users.
Another Scenario: WebDeveloper has all the themes & plugins at the ready to create a new website for a client. They create the client’s website as a subsite, and then transfer all of the content to the client’s own base of operations.
Migrate a Subsite to a Single Site Using the Export Function
Export the subsite from the Multisite Network. This creates an XML file.
Install WordPress as a new Single Site Domain for the client.
Download and activate the free WordPress Importer plugin from wordpress.org.