The Urbit Guidebook

Which ID Should I Buy?

A buyer's guide to the 5 different types of Urbit IDs: Galaxy, Star, Planet, Moon, & Comet

TL;DR

Urbit ID is a decentralized addressing system and public key infrastructure designed for Urbit OS. It is a unique number, a username, an avatar, a piece of a collectively owned network, and a key to a new digital world. Sort of like DNS, IP and a username system combined into one thing. Each Urbit ID is an ERC-721 NFT on the Ethereum blockchain.

There are 5 types of Urbit IDs, only 3 of which should be purchased, each with a different role in the network:

  1. Galaxies are likely candidates for large organizations, countries, or anything that wants to have complete control over their own networking. They spawn and sponsor stars, perform peer discovery and NAT traversal similar to DNS, provide provider-style services, and govern. There are 2^8 (256) galaxies and each can spawn 255 stars.
  2. Stars are for businesses, communities, or metropolises. Stars spawn and sponsor planets, perform peer routing, provide hosting or infrastructural services, and swap for $WSTR (Wrapped Stars). There are 2^16 (~65K) stars and each can sponsor ~65K planets.
  3. Planets are for individuals. They are your username, domain name, and crypto wallet address all wrapped into one asset. They can spawn moons.

NEVER BUY THESE:

  1. Moons are for devices. They are the IoT of Urbit. These are not independent identities. They cannot change sponsors.
  2. Comets are free identities. Anyone can boot one. They are for trying out Urbit, developing/deploying automated agents (bots), and performing otherwise "disposable" activity.

What is an Urbit ID?

Technically, Urbit ID is a decentralized addressing and public key infrastructure designed for Urbit OS. The Urbit ID registry is deployed to the Ethereum blockchain. Thus, each Urbit ID is an ERC-721 token. Functionally, Urbit ID is a unique number, a username, an avatar, a piece of a collectively owned network, and a key to a new digital world. You can think of it as your username, domain name, and crypto wallet address all rolled into one.

There are 5 different types of Urbit IDs: Galaxy, Star, Planet, Moon, and Comet. Each plays a different functional role in the network. Galaxies spawn Stars which spawn Planets which spawn Moons. Comets are free and can be easily generated by anyone. Galaxies are governance nodes, stars are infrastructure nodes, planets are personal nodes, moons are device nodes, and comets are bots.

Urbit ID was designed as the PKI, networking system and pseudonymous identity system for Urbit OS. For Urbit OS to succeed as a decentralized network, there needs to be a simple mechanism for distributing address space. Urbit ID was designed as a simple, mechanical system where addresses have value (because they’re scarce) and can be distributed in blocks to distribute authority and authentication. You can think of Urbit ID a bit like digital land—except smaller parcels (stars and planets) can always move to other regions by simply changing sponsors.

Each Urbit ID is really just a number. From that number, we generate a pronounceable name and a visually identifiable sigil. ~dalwel-fadrun is 3,509,632,436, for example. This number is a place in our Urbit ID registry which gives you access to and ownership of the network. Urbit IDs are scarce so they cost something. There are 2^32 (~4B). Since they cost something, people are less likely to spam or abuse the network. And since you need a sponsor, you have some basic form of accountability to someone—you can always change sponsors. The internet died five years ago, Urbit lives on.

Urbit ID is a pseudonymous and reputation-based identity system. There are ways to swap your ID with a nickname or dox yourself on the network if you wish. Think of an Urbit ID more like a phone number than a handle.

The Different Types of IDs

When talking about Urbit IDs to purchase, we are really only talking about three kinds: Galaxy, Star, and Planet. Moons and Comets aren’t worth buying. If they are for sale, it is a scam. Run, don’t walk, the other way. One of the most important functions of galaxies and stars is minting other identities, aka spawning. There are a total of 256 galaxies. Each galaxy can spawn 255 stars. Each star can spawn 65,535 planets. This makes for a total of ~4.3 billion planets on the Urbit network.

When deciding which Urbit ID to purchase you should consider what level of involvement you want in the network, as well as the current status of the Urbit ID. Be sure to read our How to Inspect an ID guide which goes over the difference between new and booted, spawned and unspawned, active and inactive Urbit IDs.

The sections below will detail the role of each type of Urbit ID in the network.

Galaxy

  • Example name: ~zod
  • Spawns: 2^8 Stars
  • Purpose: Governance

Galaxies are likely candidates for large organizations, countries, or anything that wants to have complete control over their own networking or play a role in governing the future of Urbit ID.

Galaxies 1. spawn and sponsor stars, 2. perform peer discovery and NAT traversal similar to DNS, 3. vote, and 4. part of an exclusive social club. Let’s break that down.

Galaxies spawn 255 stars, each star can spawn 65,535 planets. That’s a lot of address space. Galaxy holders are responsible for keeping their nodes running at all times as they provide software and network updates for their peers, also known as sponsoring stars. It’s considered bad practice to spawn and sell stars from an inactive galaxy.

On the network, galaxies perform peer discovery for their children. Simply put, this means that your galaxy tells other Urbit IDs where they can find your children so that they can communicate directly with them -- similar to asking a DNS server to tell you where to look for google.com. Thus, it is crucially important that your Galaxy be online and reachable.

Galaxy holders form a senate that can upgrade the logic of the Urbit ID system by majority vote. They convene in a private group on Urbit, a telegram channel, and an email list.

They also form a select social club.

Star

  • Example name: ~sampel
  • Spawns: 2^16 Planets
  • Purpose: Infrastructure

Stars are for businesses, communities, DAOs, or metropolises.

Stars 1. spawn and sponsor planets, 2. moderate their peers, 3. provide hosting, L2, or object storage services and 4. swap for $WSTR.

  1. A star can spawn 65,535 planets. Star holders are responsible for keeping their nodes running at all times as they provide software and network updates for their peers, also known as sponsoring planets. It’s considered bad practice to spawn and sell planets from an inactive star.
  2. Stars are natural Schelling points for services and as such can earn income by charging fees for bolt-on, provider-style services. While it is still early days on the network, we have some ideas about services stars could provide. Want to run some machine learning algorithms to auto-tag all your music files? Fine, your star has a giant machine learning cluster that's available over a pay-per-compute API. Want access to high-frequency market data? Also something you can pay for through your star. Want to buy something using bitcoin? Your star can act as a supernode charging miner-style fees.
  3. To a degree, a star is responsible for all the planets they host. If a planet you sponsor is abusive, others may ask you to take corrective action by warning or de-sponsoring the ship in question. Note that this isn’t a common occurrence; unilaterally revoking sponsorship should be considered the nuclear option. Keep in mind that sponsorship is a two-way street. If you develop a reputation for facilitating abusive planets, others ultimately have the option of ignoring you or the planets you sponsor.
  4. Stars currently can provide several services:
  • Hosting: Not every person can be expected to set up their Digital Ocean instance using terminal. Some examples of hosting services are UrbitHost, Escape Pod Store, and Tlon Corp.
  • Object Storage: It doesn’t make sense to store large media inside of a planet’s files system. Stars can provide these services via connectors that allow you to automatically upload media to a file storage service such as AWS or LFS.
  1. All unbooted stars can be swapped for Wrapped Stars ($WSTR). This means that your star must remain unbooted and have not spawned any of its planets. You can swap your stars here.

Planet

  • Example name: ~sampel-palnet
  • Spawns: 2^32 Moons
  • Purpose: Personal

Planets are for you. They are personal and permanent. You can pass your planet onto your children, your children’s children, and so forth.

Planets are your username, domain name, and crypto wallet address all wrapped into one. Your planet can also distribute software. In fact, you look up software applications by @p, an Urbit ID name such as ~sampel-palnet.

Planets can issue 2^32 moons. We’ll read more about moons in the next section, but it is worth noting that moons are not independent identities like galaxies, stars, and planets. Moons are not represented in Azimuth.

Moon

  • Example name: ~doznec-salfun-naptul-habrys
  • Spawns: N/A
  • Purpose: Device

Moons are for devices.

Moons differ from all previous Urbit IDs in that they cannot escape their sponsor. Moons are currently used as backup identities, bots, or group hosts. Hosting a group inevitably means more network traffic, and a heavily trafficked group may impact a planet’s performance. Thus one may wish to offload group hosting duties to a moon to maintain a more performant planet.

Moons are kind of like the IoT of Urbit. Someday moons are for your fleet of farming robots, your in-house factory, your network of mining GPUs.

Comet

  • Example name: ~doznec-salfun-naptul-habrys-doznec-salfun-naptul-habrys
  • Spawns: N/A
  • Purpose: Bot

Comets are for bots or for trying out Urbit. These are free identities that anyone can spin up to get on the network. Spin one up today and get on the network for free using Port. Because comets are free, many groups or other Urbit IDs might block communications with them.

Comets don’t have an OTA provider by default. So they really are for demo-mode.