I'd include Twitch/live-streaming as it's own category, while similar to Slack + Discord its focus is a 1-to-many stream + discussion Also Guestbook should pro

I'd include Twitch/live-streaming as it's own category, while similar to Slack + Discord its focus is a 1-to-many stream + discussion Also Guestbook should probably include the more generic "comments" which is similar but describes a wider range of discussion format. Edit: Oh and message groups, e.g. WhatsApp groups, which provide for semi-private online discussion.