Here are two methods for securing your data and workbook with passwords and permissions in Excel:

1. Password-protecting the Workbook:

This method restricts anyone from opening the workbook without the password.

* Open your Excel workbook.
* Navigate to the File tab.
* Click on Info.
* In the Protect Workbook section, select Encrypt with Password.
* Enter a strong password in the Password box and retype it in the Verify Password box.
* Click OK.

2. Restricting Editing with Permissions (For Users with Microsoft 365):

This method allows you to control access levels for different users (requires Microsoft 365).

* Open your Excel workbook.
* Navigate to the File tab.
* Click on Share.
* Enter the email addresses of the users you want to share the workbook with.
* Click the dropdown menu next to each email address and select the permission level:
* Can edit: Allows users to fully edit the workbook.
* Can view: Allows users to only view the workbook and make comments (if enabled).
* You can also set additional restrictions like preventing users from downloading the workbook.
* Click Send.

Important Considerations:

* Password Strength: Choose a strong and unique password that is difficult to guess.
* Password Sharing: Avoid sharing your password with anyone you don't trust completely.
* Permission Levels: Carefully consider the appropriate permission level for each user based on their needs.
* Microsoft 365 Requirement: The permission feature is only available in Microsoft 365, not the desktop-only version of Excel.
* Data Encryption: For an extra layer of security, consider encrypting your entire workbook using third-party tools (not a built-in Excel feature).

By implementing these methods, you can control access to your data and workbook, helping to prevent unauthorized viewing or modification of sensitive information.