Installation profiles are a feature in Drupal core that was added in the 5.x series. The Drupal installer allows you to specify an installation profile which defines which modules should be enabled, and can customize the new installation after they have been installed. This will allow customized "distributions" that enable and configure a set of modules that work together for a specific kind of site (Drupal for bloggers, Drupal for musicians, Drupal for developers, and so on).