Use the default if you do not want protection. Without protection, any client can access any file on your server machine.
If you want to limit access to certain files, consider using password protection, or secure SSL connections.
If you want to require a valid password before displaying a particular file, or directory of files, set up password protection. If you want data to travel over the Internet in encrypted form, set up secure SSL connections.
For example, if your server serves stock quotes, you want to verify that the client requesting the quote has paid for the quotation service. Password protection limits access to certain files.
Implementing SSL requires additional steps. If you need encryption, set up secure connections.
For example, your server provides a catalog for a mail order business and buyers submit credit card numbers over the Internet. You want to set up a secure connection for the credit card information.