Explanation

To password-protect a Microsoft Word document, follow these steps:

1. Go to the "File" menu
2. Click on "Info"
3. Click on "Protect Document"
4. Select "Encrypt with Password"
5. Enter a strong password and confirm it
6. Click "OK"

This will encrypt the document and require a password to open it.

You can also use the "File > Save As" method and select "Password" in the "Save As" dialog box, but the "File > Info > Protect Document" method provides more security options.