A comment can provide additional information to a cell. 

To Add a Comment:
1.  Click on the cell you want to add a comment to.
2.  Click on the Review tab.
3.  Click New Comment.  Enter the information you would like to associate with the cell.
4.  Click outside the Comment to close and notice a little red triange appears in the corner of the
     cell.  If you move your cursor over the cell, your comment will display.  You can size your
     comment if you would like.

Comments do not print unless you specify them to print in the Page Setup area.

1.  Click on the Page Layout tab.
2.  Click on the Print Titles icon located in the Page Setup group.
3.  Located on the third tab labeled Sheet in the middle of the screen, is an option that says
     Comments:  and the default is None.  You can decide to print the Comments at the end of
     the spreadsheet or as they are displayed on the worksheet.

To Remove a Comment:
1.  Right mouse click on the cell with the comment, and select Delete Comment.