Hierarchical deterministic wallets. One seed derives a tree of keys so backups stay simple.

The Bitcoin specification for a particular Schnorr signature scheme over secp256k1, used with Taproot spending.

The word-list standard for mnemonic seeds used by most wallets.

A derivation-path convention so the same seed can produce keys for many coins in a predictable tree.

A central bank digital currency. A digital liability of the central bank, not a commercial-bank deposit and not Bitcoin.

A large-value U.S. dollar netting system used by banks for many international USD payments.

The nested-account model banks use to pay across borders when they do not hold accounts with each other.

A decentralized identifier, a W3C-style id that can resolve to keys without a central registry.

Ethereum's fee market: a burned base fee plus a tip. It made fees more predictable and added a burn.

Proto-danksharding. Added blob space so rollups can post data far cheaper than calldata.

An Ethereum transaction mechanism that lets an externally owned account authorize persistent delegation to executable code, introduced through Pectra in 2025.

A multi-token standard that can hold fungible and non-fungible ids in one contract.

An Ethereum interface allowing a smart contract account to report whether it considers a given message signature valid.

An Ethereum interface standard for fungible token contracts, covering balances, transfers, allowances, and events.

The account-abstraction standard that adds user operations, bundlers, and paymasters without changing Ethereum consensus.

The Federal Reserve's instant-payment service for U.S. banks.

The Federal Reserve's RTGS system for U.S. dollar wholesale payments.

The Financial Information eXchange protocol used by traditional venues for orders and market data.

A global standard for richer financial messages used by payments, securities, and FX. Several crypto networks market ISO 20022 compatibility for bank rails.

The international codes for currencies (USD, EUR, XAU). Crypto tickers are informal and are not ISO 4217 assignments.

Legal Entity Identifier. A global id for companies in financial messages, including many ISO 20022 payments.

Partially Signed Bitcoin Transaction. A wallet-exchange format for hardware signers and multisig.

Real-time gross settlement. Central-bank rails that settle each payment in full, not in net batches.

Bitcoin's 2017 capacity and malleability fix. Addresses start with 3 or bc1.

The Society for Worldwide Interbank Financial Telecommunication. The messaging network banks use to instruct cross-border payments, now migrating many flows to ISO 20022.

A Bitcoin upgrade that improved privacy and scripting, used by Ordinals and many modern spends.

The Eurosystem RTGS for euro central-bank money.

TARGET Instant Payment Settlement, the ECB's instant euro rail.

A signed claim (age, license, accreditation) that a wallet can present without handing over a photocopy.