The History page allows users to view changes made to a Workflow in chronological order.
History is accessed via the main Design module:
The changes are visible per-Workflow, and log broad changes. The Action Taken column gives the class of action that triggered the log entry, and the Further Information column's content is dependant on the type of action. For instance, when modifying the Workflow Properties it'll display the Workflow's name, whereas when modifying or creating a Workflow Version, it'll list the Version number.