Microsoft Office 2010 includes a new "Protected View" that, by default, will open all Outlook attachments and documents downloaded from the Internet in "read-only" mode.

How to Tell If a Worksheet Is Protected in Microsoft Excel 2003. Protecting a worksheet in Excel 2003 prevents others users from editing it. ... How to Return to Normal View in Excel 2007.

Microsoft Excel normally does not let users change the values of protected cells. To edit a protected cell, you must first remove its protected status. You can do this using either Excel's ribbon ...