Sub-groups and channels
When to use a conversation space and when to use a noticeboard.
Both live inside a community, and both appear in your Communities tab. The difference is who can post.
A sub-group is a conversation. Everyone in it can post, like a group chat. Use one per team, per topic or per occasion — the under-14s, the fundraising committee, the summer trip.
A channel is a broadcast. Admins post and everyone else reads. Use one for announcements, newsletters and anything that must not get lost in chatter.
To create either one, open your community and choose to add a sub-group or a channel. You give it a name and a photo, pick who is in it, and it appears inside that community for its members.