Multiple Sites Using the Same Drupal Install
In a perfect world, you want all your websites to rely on the same code base. That way a fix for one site is reflected in all the sites you manage. This holds doubly true when you use any sort of framework software, such as Drupal, as there's nothing worse than going through a dozen different installs and rolling out the same patch over and over again. Fortunately it is very easy to configure Drupal to run many websites from the same install.