Excel: Adding Pop Up Notes to Cells
While Excel’s Data Validation feature is most commonly used to check data that is entered in a cell, it can also be used to place “Pop Up” notes that will display when a user selects a cell - this might be useful if you want to add some additional information or explanation to a cell entry.

To add a Pop Up
message to a cell:
Click in the cell and select Data, Validation from the Excel menu.
Select the InPut Message tab
Whenever someone selects the cell, the message will “pop up”.
