Some types of content, such as polls, typically won't require revision control. For other content that is deeper and more complex, though, such as book content, a user may wish to just automate revision tracking so it always happens.
The administrator of an OSU Drupal 6 site can do this.
For information on how to configure a node type so it automatically tracks revisions, please see the Workflow Settings Fieldset section on the Defining Your Custom Node Type page of our OSU Drupal Deep Dive technical manual.