When you sign up for a web hosting services, you need to have an official name for it. All these name can be used to point to the same web site that you hosted with us. You may have many names.
Same thing happen in Internet E-mail addresses.
Its main purpose is for group collaboration or discussion. To join the list, you need to subscribe to it. Once you are on the list, you can send E-mail to the list and all members in the list will get your message. Now Mailing List Server give you more control such that you can set a list to be moderated, member-only, or public. Shell Access You can telnet to the server and manage your web site.