Glossary

Velum terms in alphabetical order, in plain language.

Term	What it is
Alias	Unique, public name (for example `@lucia`) that points to your contact card. Pseudonymous: it doesn't say who you are.
Attestation	Apple's proof (App Attest) that the app is the original one on a real iPhone. It protects the network from spam; it isn't what protects your messages.
Bond	VEL locked by a node to raise its weight in the lottery up to ×2.
Bridge	A route a node opens and keeps up between senders and mailboxes. Messages travel over bridges.
Bucket	Fixed size each envelope is padded to: 2 KB, 8 KB, 32 KB, 128 KB, 512 KB, 2 MB or 8 MB.
Cap	1,000 M VEL: the most that can ever exist.
Carrier	Node that accepted a fragment from the sender. Earns 1 credit per receipt.
Continuous service	A node's streak of epochs with presence. It resets after more than 48 hours in a row without presence.
Courier	Node that delivered a fragment to its recipient. Earns 1 credit per receipt.
Delivery credit	A bridge's unit of work. Counts towards discovering VEL.
Device	Each phone, tablet or computer on an account. Has its own keys. Up to 5.
Difficulty	How many deliveries it takes to earn 1 VEL in an epoch. Rises with usage and at every halving.
Discover VEL	What nodes do every epoch: with the verified work of their bridges and blocks, they obtain their share of issuance, the way blocks are discovered in Bitcoin.
ECH	Encrypted Client Hello: hides which site you're connecting to from anyone watching the connection.
Envelope	A message encrypted for one specific device.
Epoch	Period after which the epoch's VEL is discovered: 1 hour on mainnet, 1 minute on the test network.

| **Faucet** | Test network account that gives away VEL and test tokens. It doesn't exist on mainnet. |

| Fragment | One of the 5 pieces of an envelope. Any 3 are enough to rebuild it. | | Full node | A node on a computer. Delivers fragments and produces blocks. | | Gateway | Public server where nodes and apps meet. It forwards; it can't read. | | Genesis | The chain's first block. Includes 100 M VEL and the test tokens. | | Halving | Every 1,051,200 epochs (about 2 years) issuance per epoch halves. | | Heartbeat | Signed message a node uses to say it's still online. | | Identity | Your chat key. Your contacts know it; it never goes on the chain. | | Invitation | Single-use link to message someone who doesn't have the app yet. Their messages wait 24 hours. | | Light node | The phone app acting as a node. Only delivers fragments; doesn't produce blocks. | | Lottery | Public draw of 3 candidate nodes per piece; the app uses the closest one. | | Mailbox | Where a device's fragments wait. It changes every day and only its owner can open it. | | Maker / taker | The order waiting in the book / the order that arrives and crosses it. The taker pays, under the general fee rule. | | ML-KEM-768 | Post-quantum key encapsulation algorithm (FIPS 203 standard). | | Multiplier | A node's tier weight when discovering VEL: ×0.50, ×0.65, ×0.85 or ×1.00. | | Network Reserve | Keyless account that keeps 20% of fees and returns 0.1% of its balance to bridges every epoch. | | Nonce | A wallet's transaction counter. Stops a transaction from being replayed. | | Oracle | VEL price in EUR, USD and USDT calculated by the network: the last-hour average (TWAP) of its market. | | Order book | List of bids and asks for a market pair, sorted by price and time. | | Prekey | A device's X25519 + ML-KEM pair that rotates every 24 hours. Provides forward secrecy. | | Proof of Delivery | Anonymous receipt system that proves a fragment arrived without saying to whom. | | Receipt | The recipient revealing a fragment's secret. No signature, no address. | | Recovery phrase | 24 words that generate all of an account's keys. Only for recovery if every device is lost. | | Reed–Solomon | Code that rebuilds an envelope from any 3 of 5 fragments. | | Reorganization | Switching to a better branch of the chain. On Velum they're usually one or two blocks. | | Sealed sender | Nothing on the outside of the envelope says who sent it. |

| **tEUR / tUSD / tUSDT** | Test tokens. Not money. |