What is Google Groups?

What is Google Groups
Google Groups is a free service from Google where groups of people have discussions about common interests. Internet users can find discussion groups related to their interests and participate in threaded conversations, either through the Google Groups web interface, or by e-mail. They can also start new groups. Google Groups also includes an archive of Usenet newsgroup postings dating back to 1981 and supports reading and posting to Usenet groups.Users can also set up mailing list archives for e-mail lists that are hosted elsewhere.

Google Groups provides two distinct kinds of groups: traditional Usenet groups, and non-Usenet groups that are more similar to mailing lists. The Google Groups user interface and help messages do not use a distinct name for mailing-list style groups, referring to both styles of group as "Google Groups".

The two kinds of groups differ both in the technology used and how they are governed. The Google Groups user interface encourages users to create new mailing-list-style groups, but does not provide any way to create a Usenet group.

Google Groups uses NNTP protocol
A Usenet group is decentralized and not hosted by any single organization. Many organizations other than Google allow Usenet groups to be read with newsreader software that uses the NNTP protocol. Most Usenet groups are unmoderated. Google recognizes the X-No-Archive header and archives messages containing it for only seven days.

A regular Google Group is hosted by Google. These groups can be accessed using a web browser or by subscribing to receive email, but can't be accessed using a Usenet news reader. They have one or more owners who decide who is allowed to subscribe to the group and whether non-members can access the group. This form of governance is similar to that provided by many other mailing list providers. Google Groups also allow for a group to be an archive of a group hosted on another mailing list server.