Excel offers two main ways to protect your workbooks or sheets from unauthorized editing:

1. Protect Workbook Structure:

This option safeguards the overall structure of your workbook, preventing actions like:

* Adding, deleting, or hiding worksheets
* Renaming worksheets
* Changing the workbook layout

Here's how to enable it:

1. Go to the "Review" tab.
2. Click "Protect Workbook" in the "Changes" group.
3. Optional: Add a password. Entering a password in the "Password" box restricts unprotecting the workbook without the password.
4. Click "OK" to confirm.

Important: Remember the password if you choose to set one. Excel cannot recover lost passwords.

2. Protect Sheet:

This method provides granular control over individual worksheets within your workbook. You can choose to:

* Lock all cells and allow specific ones to remain editable.
* Grant permission for certain actions like formatting cells, inserting rows/columns, or using sorting/filtering tools.

Here's the process:

1. Select the worksheet you want to protect.
2. Go to the "Review" tab.
3. Click "Protect Sheet" in the "Changes" group.
4. Under "Protect sheet and contents of locked cells", check the box.
5. In the "Allow all users of this worksheet to" section, choose the actions you want to permit (formatting cells, inserting rows, etc.).
6. To unlock specific cells for editing, format those cells:
* Select the cells you want to unlock.
* Right-click and choose "Format Cells".
* Go to the "Protection" tab.
* Uncheck the "Locked" box.
7. Click "OK" to activate sheet protection.

Using a password with sheet protection:

1. Follow steps 1-6 above.
2. Check the box next to "Use a password to unprotect sheet".
3. Enter and confirm your password in the designated fields.
4. Click "OK" to activate sheet protection.

Remember: Anyone with the password can unprotect the workbook or sheet. Keep it secure and avoid sharing it with unauthorized users.

By following these steps, you can ensure that your workbooks and sheets remain secure and prevent accidental or unauthorized modifications.