Google Groups can be used both as a mail list and an online forum or bulletin board.  A mail list is group of email addresses that can be contacted via one email address.  For example, you may have a group called “Cheeseburger Lovers.”  You can set up a Google Group and email the entire group by sending an email to cheeseburger-lovers@googlegroups.com.  Instead of emailing to the group, members can post to a Group web site.  This differs from email broadcast software in that if someone replies to an email sent to the group, the whole group gets that email also.  You can configure Google Groups so that email is a one way announcement, but if that’s what you’re after, you might as well use proper email broadcast software such as Mail Chimp.

To create a group

https://groups.google.com/d/creategroup

To subscribe to a group

[Group Name]+subscribe@googlegroups.com
(replace any spaces with a dash in the group name)

 FAQ

Google Group FAQ’s