title: What are the differences between 'revert', 'amend,' 'rollback', and 'undo' a commit?
body: <p>To help in my knowledge of git so I can use it day to day, what is the difference between:</p>
  <ul>
  <li>revert</li>
  <li>amend</li>
  <li>rollback</li>
  <li>undo</li>
  </ul>
  <p>What are they and what do they do?</p>