Start an Online Discussion Community
Google Groups
https://support.google.com/groups/answer/2464926?hl=en
Here's how to create a group:
Go to Google Groups.
Near the top left corner, click Create group.
Describe the group. Tip: If you're not sure what to include, you can learn more about establishing general information and settings.
Choose the type of group you want to create. Tip: If you're not sure what to choose, you can learn about selecting group types.
Choose who can join, post, and see topics in your group. Tip: If you don't know what to pick, you can learn more about setting basic permissions.
Near the top left corner, Click Create group button.
Yahoo groups
Linkedin Groups
https://help.linkedin.com/app/answers/detail/a_id/6/~/creating-a-group
facebook groups
https://www.facebook.com/help/167970719931213
To create a group:
From your home page, go to the Groups section on the left side menu and click Create Group.
Click + Create New Group at the top of the page. A window will appear, where you'll be able to add a group name, add members and select the privacy settings for your group.
Click Create when you're done.
Ning
Ning is an online platform for people and organizations to create custom social networks, launched in October 2005. Wikipedia