A mailing list is something like a "group" in your email address book.

There are some important differences:

• The list is online.
• Everyone's email address is safely invisible.
  
• Members of the list all share a single distribution list.
• Members keep their own email address up to date or else they stop receiving messages from the group.
• The list can be moderated so irrelevant messages do not get sent out.
• It is as easy to use the list as it is to use an address in your email directory.
• Each list has a particular "topic of interest."