You can add comments to items in your visual. These comments are labeled with your user name and the date at which you made the comment.
To add a comment, select the item you wish to add it to and click Add Comment in the Review tab. A text entry box appears; type your comment in this box. When you're done, click somewhere else or press the Esc (or Escape) key to close the box.

Your initials and the comment number, as highlighted bold text, are placed on the item. To read the comment, position your cursor over this text.

To edit the comment, click on the comment label.
Deleting all of the text in a comment and then closing the text entry box will delete the comment.
The Review tab also contains buttons for hiding or showing the comments in the visual. (Show Comments), And for navigating through the comments in numerical order (Next Comment and Previous Comment).