Modern Drupal (8+) has automated translation downloads built-in so you can forget about this page.
For Drupal 7, you can easily install Drupal localized with Localized Drupal. You can also set it up to contribute to these translations right from your Drupal site! For already installed sites, use the Localization update module to download the right translation files for the right modules you use and Localization client module to contribute back from the comfort of your site.
More information on download options.
