If you have sensitive data you'd like to keep from prying eyes in a Microsoft Excel file, the easiest way to protect it is with Excel's built-in password tools.

Open the spreadsheet you want to protect in Excel, click the "Review" tab and then click "Protect Sheet" in the Changes group to display the Protect Sheet dialog.

If you want to set an expiration date and password when sharing Excel files online, here is how you can do that. It is possible to do both of them when using Excel Online.

To lock your cells in Microsoft Excel, you just need to head into the program's "Protection" tab. Locking a cell in Excel will make it so viewers can't change the data inside of that cell, which ...