Pop-up comments are a great way to add extra information to your graphics in Excel. To add a pop-up comment, first select the cell that you want to add the comment to. Then, click the Insert tab on the ribbon and click the Comment button in the Comments group. A comment box will appear. Type your comment into the box and click the Save button. Now, when you hover over the cell that you added the comment to, a pop-up box will appear with your comment. This is a great way to add extra information about a data point or to provide instructions for someone viewing your spreadsheet.