This document provides instructions for setting up a WordPress Multisite installation in 20 minutes. WordPress Multisite allows creating a network of websites from a single WordPress installation that shares themes, plugins, and users. Key benefits include running unlimited websites from one account/database, sharing resources across sites, and managing multiple sites from one dashboard. Major steps include adding Multisite configuration to wp-config.php, replacing .htaccess, and creating a blogs.dir directory. Popular plugins for Multisite include domain mapping and sitewide tags.