Scuttlebutt is a peer to peer, decentralized social media protocol. Meaning it is not controled by a single company, or hosted on single server. It has different clients and ways of interacting with the people using it, and connection is facilitated using identity keys (like the one above). Personal keys are exchanged using a "Pub" server, which acts as a connection point between individuals. As your friend network grows, everyone in your network holds a copy of all shared communications on their own computer. Because of this, the network is completely decentralized, and nearly imposible to take down. To take it down, all copies, on every computer would have to be deleted. This makes Scuttlebutt highly resilient, and censorship resistant. It also has the benefit of being largely usable offline, requiring only a brief period of internet connection to download new conversations, and upload any replies you may have written while offline, to the distributed network.
This is the technical description of why it's cool, but the fact that people from all corners of the world are using it is why its fun to use.
For more information, go → here.