By Conrad Carlberg

These days, almost everyone has Excel workbooks that other people use. Whether the workbooks are simultaneously opened and shared by others or they’re just available to others through shared folders, your colleagues probably have access to your work. And that means you need to look after your work.

Excel makes protecting your work pretty easy. Open a worksheet that you want to protect and go to the Home tab. Choose Format in the Cells group and click Protect Sheet. The Protect Sheet dialog box appears, giving you various options for what to protect. If you want to protect any cells against being changed, you need to lock them first. Select those cells and choose Lock Cells in the Protect Sheet drop-down. Then protect the worksheet.

Make sure to select the Protect Worksheet and Contents of Locked Cells check box. Provide a password in the Password to Unprotect Sheet box. If you do this, you’re better protected against other users changing your values and formulas.

Worksheet protection isn’t completely secure. You can buy a password cracker — software that figures out your password — and if you can buy it, that means other people can buy it, too. Free VBA code is floating around the Internet that will do the same thing. But unless you need to protect your work from someone who’s both knowledgeable and really determined, Excel’s protection is probably sufficient. If you want something that’s easy to hack, buy an iPhone.