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.

There are several options available to you to protect your Excel file with a password. Remember that once you protect the Excel file, you cannot open it without entering the password.

If you would like to make sure that your Excel spreadsheet data is secure this guide will show you how to password protect and hide worksheets ...

Go to Excel File > Info > Protect Workbook > Protect Current Sheet. Enter the password to protect the sheet. Select the checkmark beside the required options that other users can access and click OK.

It is possible to create a macro in an Excel sheet that unlock the sheet which is already protected by a password. Users can easily prepare a document in the sheet and then lock it again with a ...

You can make Excel always open old spreadsheets in Protected View. Enable or disable Protected View using in-built setting, Group Policy, Registry.

However, if you open a protected Excel file in the browser edition, you can see hidden formulas, but you can’t modify them. For most sheets, hiding formulas is overkill but easily implemented.