A way to protect your worksheet or workbook. When you protect worksheet or workbook elements with a password, it is very important that you remember that password. Without it, there is no way to unprotect the workbook or worksheet. You should always use strong passwords that combine uppercase and lowercase letters, numbers, and symbols. Weak passwords don't mix these elements. Strong password: Y6dh!et5. Weak password: House27. Use a strong password that you can remember so that you don't have to write it down.