For all the other commenters who couldn't understand what the heck this is (like myself)... Wikipedia at least gives a fairly straightforward explanation [1]:
> Urbit is a decentralized personal server platform. The platform seeks to deconstruct the client-server model in favour of a federated network of personal servers in a peer-to-peer network with a consistent digital identity.
> The Urbit software stack consists of a set of programming languages ("Hoon," a high-level functional programming language, and "Nock," its low-level compiled language); a single-function operating system built on those languages ("Arvo"); a personal address space, built on the Ethereum blockchain, for each instance of the operating system to participate in a decentralized network ("Azimuth"); and the decentralized network itself, an encrypted, peer-to-peer protocol running on top of the User Datagram Protocol.