How to protect and password-protect an Excel worksheet or workbook?

To protect and password-protect an Excel worksheet or workbook, follow these steps:

1. Open the Excel worksheet or workbook that you want to protect.
2. Click on the "File" tab in the top-left corner of the Excel window.
3. From the drop-down menu, select "Protect Workbook" or "Protect Sheet" depending on what you want to protect.
4. In the "Protect Workbook" or "Protect Sheet" dialog box, you will see several options to choose from.
5. If you want to password-protect the worksheet or workbook, choose the option "Protect Workbook or Protect Sheet with a password."
6. Enter a password of your choice in the "Password" field. Make sure to choose a strong, unique, and memorable password. You can also use the "Password Hint" field to provide a hint to help you remember the password.
7. Click on the "OK" button to save the password and apply the protection.
8. If you have chosen to protect a sheet, you may also select specific actions that users are allowed or not allowed to perform in the "Allow all users of this worksheet to" section.
9. After making all the desired selections, click on the "OK" button to enable the protection.
10. Excel will prompt you to confirm the password. Re-enter the password in the confirmation box and click on the "OK" button.

Now, your Excel worksheet or workbook is protected and can only be accessed by entering the correct password.