Note: All Excel protection is relatively weak. It is useful to stop casual users but it is not for top secret information.
If you are worried about changes to the structure of your workbook (the sheet names, number of sheets, the order they are in, whether they are hidden or visible etc), you can even protect this (and sometimes this is recommended when you want to hide the source information).
To follow along go to 19.9
Under the Review tab, you can click on Protect Workbook and add a password (again a password is not required unless you really don’t want someone to make changes). Note that this is different from the Protect Sheets. You can choose to Protect Workbook and not sheets are vica versa. Before you do this the workbook must be in the format you want e.g. first hide a sheet, then protect the workbook.
When you do this, if you try any thing with the sheets you will notice that most of the options are greyed out and cannot be used (this spreadsheet has a sheet that is hidden but as you can see you don’t have an option to unhide it)