Multisite

The following guide will highlight the manual steps required to set up a Drupal multisite. This guide is a work in progress with only some example configurations presented. Other options are available, such as HTTPS, other Web servers and databases, and more refined virtual host configurations, etc.

The primary reason for using a multisite Drupal setup is to save your time when you manage more than one Drupal site running the same version of Drupal core. Each time a new Drupal core update is released, you would only have to perform that update on one codebase set instead of doing it for each site. But there are drawbacks.  These are mitigated, however, if you're using the Aegir hosting system.