Identity
Urbit ID
Urbit ID is the naming and routing system. Five ranks: galaxies, stars, planets, moons, comets. Ordinary people usually want a planet — a four-syllable name like a callsign. Azimuth, on Ethereum, is the ledger that says which keys speak for which name.
A comet is free and disposable. A planet is scarce and social. Moons hang off planets the way workstations hang off a person. Stars and galaxies are infrastructure. Keep the master key like you would keep a physical seal.