1 This directory is reserved for core module files. Custom or contributed

     2 modules should be placed in their own subdirectory of the sites/all/modules

     3 directory. For multisite installations, they can also be placed in a subdirectory

     4 under /sites/{sitename}/modules/, where {sitename} is the name of your site

     5 (e.g., www.example.com). This will allow you to more easily update Drupal core files.

     6 

     7 For more details, see: http://drupal.org/node/176043

     8