Now we have a functional Drupal site. Can we proceed with Ubercart installation? Not yet! First we have to install a few more Drupal modules.
Drupal third-party modules are not part of the core, and they are created by individual programmers or companies. They add extra functionality to Drupal or they enhance an existing functionality. You can see a full list of all the available Drupal modules at http://drupal.org/project/Modules.
Actually, the only module that is necessary for Ubercart to work is Token.
As we can read at the home page of this module, http://drupal.org/project/token :
Tokens are small bits of text that can be placed into larger documents via simple placeholders, like %site-name ...