In this hour, you saw how Drupal is organized and how it is used in various websites. Drupal's structures—both the structure of the organization and the structure of its software—show you how you can feel comfortable downloading new modules for your website from www.drupal.org.
Q. What is Drupal's copyright status?
A. Drupal is distributed under the GNU General Public License version 2 or later (www.gnu.org/copyleft/gpl.html). All contributed modules by third parties must be distributed under the same license. Drupal is free in the four ways covered by the GPL—free to use it, free to change it, free to share it, and free to share changes you make to it. Obviously, to make this possible, the source code is distributed.
Q. Is Drupal object-oriented software?
A. Drupal 7 is the first version of Drupal to require PHP 5, so it is the first version that could use the object-oriented implementations that PHP 5 supports. Drupal's design is object oriented in the sense that it adheres to the basic principles of object-oriented software, particularly in its use of the hook mechanism that allows any module to extend (override) default functionality.