What is the function of the "Details" tab" when responding to a question?

When you are preparing a proposal, your free-form text responses might go through many rounds of revision. You might have many different authors working on a response. 

When you click on a Question, the last tab. Details show the history of your response. 

 

You can not only see who has been working on a response, but you can click on the icon at the far right and compare any two versions in history. You can also leave comments and see workflow changes in this tab.