How to use this glossary
Every entry has a stable anchor. To deep-link a single definition into a chat, a guide, or a pull request, copy the URL with the term's anchor — for example /guides/glossary/#atomic-swap. Definitions are written to be quotable: short summary first, longer context after. Where a term has its own pillar guide on this site, we link to it.
Term index
- Account model
- Atomic swap
- Bridge
- Chain analysis
- EDD (Enhanced Due Diligence)
- Fixed rate
- Float rate
- HTLC (Hash Time-Locked Contract)
- Liquidity aggregator
- Memo / destination tag
- Mempool
- Mixer / CoinJoin
- No-KYC (no Know-Your-Customer)
- Non-custodial
- Pegged stablecoin
- Pseudonymous vs anonymous
- Refund-first policy
- Ring signatures
- RingCT (Ring Confidential Transactions)
- Seed phrase
- Self-custody
- Single-use deposit address
- Slippage
- Stealth address
- UTXO (Unspent Transaction Output)
- Wrapped token
- zk-SNARK
Definitions
Account model
The balance-tracking design used by Ethereum and most newer chains.
In an account-based chain, each address has a single balance that is updated on each transaction. Contrast with UTXO chains, where balances are computed from the set of unspent outputs. Account-based chains are simpler for smart contracts and worse for transaction privacy — your full balance is visible on a block explorer at any moment, whereas UTXO chains let you split holdings across many addresses with coin-control tooling.
Atomic swap
A cross-chain trade with zero third-party custody at any moment.
A cryptographic protocol that lets two parties exchange assets on different chains without a custodian. Either both legs settle (both parties get what they wanted) or both legs roll back (both parties keep what they started with) — there is no possibility of one side stealing. The most prominent implementations are BTC ↔ XMR atomic swaps via COMIT, Farcaster, and the Haveno marketplace. See our atomic swap guide for the deep dive.
Bridge
A protocol that moves a token from one blockchain to another.
A bridge wraps a native asset on chain A as a synthetic token on chain B — e.g. Wormhole, LayerZero, Stargate. Bridges have been the largest loss category in DeFi (multi-hundred-million-dollar bridge hacks happen every year). A no-KYC swap routes natively on each chain (no wrapped tokens) and is therefore a strictly safer way to move value between chains for most users.
Chain analysis
The industry of tracing crypto transactions to identify the parties involved.
Companies like Chainalysis, Elliptic, and TRM Labs maintain enormous graphs of address clusters tagged with provenance (exchange A, service B, sanctioned wallet C). Their products are sold to exchanges, regulators, and law enforcement. Chain analysis is the practical reason address hygiene matters — if you reuse addresses or merge clean and dirty UTXOs, you make their job trivial.
EDD (Enhanced Due Diligence)
A formal compliance term meaning "extra identity checks".
EDD is what the regulated financial industry calls KYC-with-extra-scrutiny applied to flagged transactions. In the no-KYC swap context, "risk-based EDD" in a service's terms is the operative phrase: it means the service reserves the right to demand identity verification on transactions that trip their risk engine. Refund-first policies, by contrast, do not escalate to EDD — they refund.
Fixed rate
A swap rate type that locks the quote for a fixed window.
In fixed mode, the rate displayed in the widget is locked for typically ten minutes from deposit detection. If your deposit confirms within the window at the locked rate, you receive exactly the quoted amount. If the deposit arrives late, the order page will ask whether to refund or accept the current market rate. Fixed rates have wider spreads than float rates (the service hedges the price risk) and are recommended for volatile markets where rate certainty matters.
Float rate
A swap rate type that executes at market price at confirmation time.
In float mode, the rate displayed in the widget is indicative — the actual rate is set at the moment your deposit confirms on-chain. If the market moves in your favour during confirmation, you keep the upside; if it moves against you, you accept it. Float rates have tighter spreads than fixed rates because the service does not need to hedge price risk during the confirmation window. Recommended for calm markets and patient users.
HTLC (Hash Time-Locked Contract)
A smart-contract primitive enforcing atomicity in cross-chain swaps and Lightning routing.
A Bitcoin-script (or smart-contract) construct that says "the funds can be claimed by anyone who reveals the preimage of this hash within a time window; if no one reveals before the deadline, the original owner can reclaim". HTLCs are the building block for atomic swaps and for Lightning Network multi-hop payments. The mechanism ensures that either both sides of a swap settle, or both sides roll back — enforced by cryptography rather than by trust.
Liquidity aggregator
A service that routes orders across multiple liquidity venues to find the best price.
Instead of holding inventory or running an orderbook, an aggregator polls multiple upstream venues (exchanges, OTC desks, DEXs) for live quotes and routes the user's order through the venue offering the best rate net of fees. NoKYCSwap is a non-custodial aggregator. The user-visible effect is a single widget that quotes prices competitive with going direct to any individual venue.
Memo / destination tag
An extra field required by some chains/exchanges to route deposits correctly.
XRP, Stellar, TON, EOS, Cosmos and others use destination tags or memos to identify which user owns a deposit at a shared address. Most exchanges share a single deposit address per asset across all users; the memo tells them whose balance to credit. Self-custody wallets typically do not need memos. A missing memo on a deposit can delay or strand funds, which is why swap widgets prompt for it on memo-aware chains.
Mempool
The pool of unconfirmed transactions waiting to be included in a block.
Each blockchain node maintains a mempool of pending transactions broadcast by users but not yet mined into a block. During congestion, the mempool grows and miners include the transactions paying the highest fee first. Bitcoin fee market dynamics are driven by mempool depth: more pending transactions, higher fees needed to confirm quickly. The mempool is publicly observable on each node.
Mixer / CoinJoin
A protocol for combining many transactions to obscure individual flows.
CoinJoin is a Bitcoin technique where multiple users pool their UTXOs into a single transaction with multiple outputs, breaking the deterministic link between any single user's input and their output. Wasabi Wallet and Whirlpool (Samourai) are mainstream implementations. Custodial mixers (Tornado Cash, deprecated Bitcoin tumblers) are a different category and have been subject to regulatory action in multiple jurisdictions.
No-KYC (no Know-Your-Customer)
No identity check required to use the service.
A service operates "no-KYC" when it never requires identity verification, government-issued ID, selfie, or address proof to use its core function. For non-custodial swap aggregators, this is the default — there is no account, no email, nothing to verify. KYC is required for custodial services because the custodian holds your funds and is regulated as a money-services business in most jurisdictions. Non-custodial swaps, by contrast, never hold your funds, so the regulatory rationale for KYC does not apply.
Non-custodial
A service that never holds your funds, even momentarily as a balance.
A non-custodial service does not hold user balances. In a swap context, funds transit through a deposit address that is single-use: deposited from your wallet, routed by the aggregator, and paid out to your destination wallet — never resting in a custodian-controlled balance attributable to you. This is architecturally different from a centralised exchange (Binance, Kraken) where you deposit, your balance is held by the exchange, you trade, and you withdraw.
Pegged stablecoin
A token designed to track the value of an external asset, usually USD.
USDT and USDC are pegged stablecoins backed by USD-denominated reserves. The peg is maintained by the issuer's commitment to redeem 1:1 for fiat. DAI is also pegged but maintained algorithmically and via over-collateralisation rather than by a central issuer. Peg deviations can occur (USDC briefly traded at $0.87 during the SVB banking crisis in March 2023) and are an important risk factor for stablecoin holders.
Pseudonymous vs anonymous
Bitcoin is pseudonymous; Monero is anonymous (functionally, on-chain).
A pseudonymous system identifies users by pseudonyms (addresses) that are stable enough to follow over time — Bitcoin's addresses are pseudonyms, not identifiers, but they can be linked to identities via off-chain information (KYC withdrawals, IP correlation, public attribution). An anonymous system makes that linking computationally infeasible at the protocol level — Monero is the canonical example. Most cryptocurrencies are pseudonymous; only a handful are anonymous.
Refund-first policy
When an order is flagged by upstream compliance, the user is refunded — not asked for identity.
A flagging-policy posture where the service's response to a flagged order is to refund the deposit (or release at market rate at user's choice), never to demand identity verification. NoKYCSwap operates a refund-first policy in writing. The alternative is "risk-based EDD" — enhanced due diligence — which is KYC by another name.
Ring signatures
Cryptographic technique that hides the sender among a group of possible senders.
A ring signature is a digital signature produced jointly by a group of public keys, in such a way that the verifier knows the signer is one of the group but cannot tell which one. Monero uses ring signatures of size 16 to obscure the sending address of every transaction — each XMR transaction looks like it could have come from any one of 16 possible source addresses. Combined with stealth addresses and RingCT, this gives Monero its privacy-by-default property.
RingCT (Ring Confidential Transactions)
Monero's mechanism for hiding transaction amounts on-chain.
Pedersen commitments combined with range proofs (originally Borromean signatures, now Bulletproofs) that allow Monero to verify a transaction's validity — inputs equal outputs, no money is created — without revealing the actual amounts. Every Monero transaction has an obscured amount alongside an obscured sender (ring signature) and obscured recipient (stealth address).
Seed phrase
The 12 or 24 words that recover your wallet.
A BIP-39 seed phrase is a human-readable encoding of the random entropy that generates your wallet's private keys. From the seed, every key can be regenerated. Storing the seed offline (paper, metal plate) and never digitally is the basic safety practice. Loss of the seed means loss of the funds; exposure of the seed means complete compromise of the wallet.
Self-custody
You hold the private keys; no third party can spend your funds.
A wallet is self-custodial if you (and only you) control the private keys. Most popular wallets (MetaMask, Phantom, Monero GUI, Sparrow) are self-custodial. Hosted wallets (Binance, Coinbase's "wallet" tier in some configurations) are not — the provider holds the keys on your behalf. Self-custody is a prerequisite for any privacy-meaningful operation; if the custodian holds your keys, the custodian holds the privacy too.
Single-use deposit address
A swap deposit address that is retired after one transaction.
When you open a swap, the aggregator generates a fresh address that will accept exactly one deposit. After the swap settles (or the time-lock expires), the address is retired and never reused. This protects against accidental cross-orderaddress collisions, makes per-order accounting trivial, and reduces the privacy surface compared to shared deposit addresses used by some exchanges.
Slippage
The difference between the expected rate at quote time and the actual rate at execution.
In an instant-swap context, slippage matters most for float-rate orders: between the moment you sign the order and the moment the deposit confirms, the market may have moved. The float quote you saw is indicative; the actual execution rate reflects market conditions at deposit confirmation. Fixed-rate orders eliminate slippage in exchange for a slightly wider initial spread.
Stealth address
A one-time-use recipient address derivable only by the recipient.
When you send XMR to someone, the actual on-chain address that receives the funds is a fresh, one-time-use stealth address derived from the recipient's public view key. The recipient can scan the chain and recognise their incoming transactions; no one else can link a stealth address to its owner. Combined with ring signatures (sender obscured) and RingCT (amount obscured), stealth addresses give Monero its three-property privacy.
UTXO (Unspent Transaction Output)
The basic unit of value on Bitcoin and Bitcoin-family chains.
Bitcoin tracks balances as a set of unspent transaction outputs. When you "spend" Bitcoin, you consume one or more existing UTXOs as inputs and create new UTXOs as outputs (one to the recipient, one to yourself as change). This contrasts with account-based chains (Ethereum), where balances are tracked as numerical balances per address.
Wrapped token
A representation of an asset from another chain, custodied by a wrapping facility.
WBTC on Ethereum is a wrapped Bitcoin token: each WBTC is backed by one BTC held by BitGo. The wrapping facility (BitGo) is the custodian; the WBTC is fungible inside EVM DeFi. Wrapped tokens introduce custody risk (the custodian could be compromised) and political risk (the custodian could refuse to wrap or unwrap based on KYC). No-KYC swaps replace the wrap/unwrap operation with a swap, removing the custodian.
zk-SNARK
A type of zero-knowledge proof used by Zcash, Pirate Chain, and others.
Zero-Knowledge Succinct Non-interactive ARgument of Knowledge. A cryptographic proof that lets the prover convince a verifier that they know some secret information without revealing what it is. In privacy-coin contexts, zk-SNARKs let users prove "I have a valid coin to spend" without revealing which coin, how much, or to whom. Zcash, Pirate Chain (ARRR), Firo (Lelantus Spark), and various L1/L2 privacy projects use zk-SNARK variants.
