When you create your website on our service, you will be asked to give it a "short name," which is a brief one-word name for your site that must be unique across our entire service, and we give you a built-in hostname based on that.
For example, if you choose example as your site's short name, you will always be able to access it as http://example.nfshost.com/.
If you don't want DNS or a domain of your own, you're welcome to use this name for your site at no additional cost. If you do use a domain of your own, then having your site available under this alternate name may help you troubleshoot any problems during the setup process, as well as provide a backup if there is ever a problem with your domain.