If you are running more than one Drupal site, you can simplify management and upgrading of your sites by using the multi-site feature. Multi-site allows you to share a single Drupal installation (including core code, contributed modules, and themes) among several sites.

This is particularly useful for managing the code since each upgrade only needs to be done once. Each site will have its own database and its own configuration settings, so each site will have its own content, settings, enabled modules, and enabled theme. However, the sites are sharing a code base and web document root, so there may be security concerns (see section below for more information).
Overview of the Process

To create a new site using a shared Drupal code base you must complete the following steps:

   1. Create a new database for the site.
   2. Create a new subdirectory of the 'sites' directory with the name of your new site (see below for information on how to name the subdirectory).
   3. Copy the file sites/default/default.settings.php into the subdirectory you created in the previous step. Rename the new file to settings.php.
   4. Adjust the permissions of the new site directory, and grant write permissions on the configuration file
   5. Make symbolic links if you are using a subdirectory such as example.com/subdir and not a subdomain such as subd.example.com (see the subdirectory multi-site section below for details).
   6. In a Web browser, navigate to the URL of the new site and conti