Hacker News

https://briarproject.org/how-it-works/

The briar mesh is via peer to peer Bluetooth / wifi connections but it is a mesh via briar message passing

In more technical terms, each forum/group/blog has a distribution graph where the nodes are subscribers and the edges are a subset of contact relationships (specifically, the subset that have chosen to reveal the subscription to each other).

So if your friend group is at a concert and the internet is down you can have a forum where y'all call still communicate, with the caveat that only people in the group will mesh/proxy messages once in range.. the benefit of this is that nobody outside the group can see the message activity, if one person makes it to the internet all messages will sync and when they go back to the concert the offline members will see internet messages.