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Ultimate Blockchain Glossary

by | Aug 30, 2019 | Blockchain, English, Tech

This is your go-to blockchain dictionary for all those words that are used frequently in the blockchain.

You will notice that each word is “labelled” (in brackets) with the concept it relates to (e.g. Ethereum):

  • Account (Blockchain): An object containing an address, balance, nonce, and optional storage and code. An account can be a contract account or an externally owned account (EOA)
  • Address (Blockchain): On Ethereum, most generally, this represents an EOA or contract that can receive or send transactions on the blockchain. More specifically, it is the rightmost 160 bits of Keccak hash of an ECDSA public key. On Bitcoin, an address looks like 1FfmbHfnpaZjKFvyi1okTjJJusN455paPH. It consists of a string of letters and numbers. It’s really an encoded base58check version of a public key 160-bit hash. Just like you ask others to send an email to your email address, you would ask others to send you bitcoin to one of your bitcoin addresses. Learn more about Bitcoin address here.
  • Assert (General): In Solidity, assert(false) compiles to 0xfe, an invalid opcode, which uses up all remaining gas and reverts all challenges. When an assert() statement fails, something very wrong and unexpected is happening, and the code needs to be fixed. In programming, it is commonly used to check for conditions that should never, ever occur.
  • Big-Endian (General): A positional number representation where the most significant digit is first. The opposite of little-endian, where the least significant digit is first.
  • BIPs (Bitcoin): Stands for “Bitcoin Improvement Proposals”. A set of proposals that members of the Bitcoin community have submitted to improve Bitcoin. For example, BIP-21 is a proposal to improve the Bitcoin uniform resource identifier (URI) scheme. A list of BIPs can be found here.
  • Block (Blockchain): A grouping of transactions, marked with a timestamp, and a fingerprint of the previous block. On certain blockchains, the block header is hashed to produce a proof-of-work, thereby validating the transactions. Valid blocks are added to the main blockchain by network consensus. A random block from the bitcoin network can be found here.
  • Bytecode (General): An abstract instruction set designed for efficient execution by a software interpreter or a virtual machine. Unlike human-readable source code, bytecode is expressed in numeric format. More about bytecode here.
  • Byzantine Generals Problem (Blockchain): A reliable computer system must be able to cope with the failure of one or more of its components. A failed component may exhibit a type of behavior that is often overlooked — namely, sending conflicting information to different parts of the system. The problem of coping with this type of failure is expressed abstractly as the Byzantine Generals Problem.
  • Byzantium fork (Ethereum): The first of two forks for the Ethereum Metropolis development stage. It included EIP-649: Metropolis Difficulty Bomb Delay and Block Reward Reduction, where the Ice Age was delayed by 1 year and the block rewards were reduced from 5 to 3 ether.
  • Coinbase (Blockchain): A special field used as the sole input for coinbase transactions. The coinbase allows claiming the block reward and provides up to 100 bytes for arbitrary data. Not to be confused with Coinbase transaction. Also, Coinbase is the name of one of the biggest crypto exchanges.
  • Coinbase Transaction (Bitcoin): The first transaction in a block. Always created by a miner, it includes a single coinbase.
  • Cold storage (Blockchain): Refers to keeping a reserve of bitcoin or other cryptocurrencies offline. Cold storage is achieved when private keys are created and stored in a secure offline environment. Cold storage is important for anyone with crypto holdings. Online computers are vulnerable to hackers and should not be used to store a significant amount of bitcoin.
  • Colored coins (Bitcoin): An open-source Bitcoin 2.0 protocol that enables developers to create digital assets on top of bitcoin blockchain utilizing its functionalities beyond currency.
  • Confirmations (Blockchain): Once a transaction is included in a block, it has one confirmation. As soon as another block is mined on the same blockchain, the transaction has two confirmations, and so on. On the Bitcoin blockchain, six or more confirmations are considered sufficient
  • Compiling (General): Converting code written in a high-level programming language into a lower-level language (e.g. EVM bytecode)
  • Consensus (Blockchain): When numerous nodes — usually most nodes on the network — all have the same blocks in their locally validated best blockchain. Not to be confused with consensus rules.
  • Consensus Rules (Blockchain): The block validation rules that full nodes follow to stay in consensus with other nodes. Not be confused with consensus.
  • Constantinople Fork (Ethereum): The second part of the Metropolis stage, originally planned for mid-2018. Originally it was expected to include a switch to a hybrid proof-of-work/proof-of-stake consensus algorithm, but this was delayed. Here you can track the changes on Constantinople.
  • Contract Account (Ethereum): An account (usually in Ethereum, or a general-purpose blockchain, e.g. EOS) containing code that executes whenever it receives a transaction from another account.
  • Contract Creation Transaction (Ethereum): A special transaction, with the “zero address” as the recipient, that is used to register a contract and record it on the Ethereum blockchain (see “zero address”)
  • DAO (Ethereum): Stands for “Decentralised Autonomous Organization”. A company or other organization that operates without hierarchical management. Just imagine the possibilities! Also may refer to a contract named “The DAO” launched on April 30, 2016, which was then hacked in June 2016; this ultimately motivated a hard fork (codenamed DAO) at block #1.192.000, which reversed the hacked DAO contract and caused Ethereum and Ethereum Classic to split into two competing systems.
  • DApp (Blockchain): Stands for “Decentralized Application”. At a minimum, it is a smart contract and a web user interface. More broadly, a DApp is a web application that is built on top of open, decentralized, peer-to-peer infrastructure services. In addition, many DApps include decentralized storage and/or a message protocol and platform. Find a list of reviewed Dapps here.
  • Deed (Ethereum): Non-fungible token (NFT) standard introduced by the ERC721 proposal. Unlike ERC20 tokens, deeds prove ownership and are not interchangeable, though they are not recognized as a legal document in any jurisdiction — at least not currently (see also “NFT”).
  • Difficulty (Blockchain): A network-wide setting that controls how much computation is required to produce proof of work.
  • Difficulty retargeting (Blockchain): A network-wide recalculation of the difficulty that occurs on a time basis. On the Bitcoin blockchain, the retargeting is once every 2,016 blocks and considers the hashing power of the previous 2,016 blocks.
  • Digital Signature (General): A short string of data a user produces for a document using a private key such that anyone with the corresponding public key, the signature, and the document can verify that the document was “signed” by the owner of that particular private key, and the document was not changed after it was signed.
  • Double Spending (Bitcoin): Double spending is the result of successfully spending some money more than once. Bitcoin protects against double-spending by verifying each transaction added to the blockchain to ensure that the inputs for the transactions had not previously already been spent.
  • ECDSA (General): Stands for “Elliptic Curve Digital Signature Algorithm”. A cryptographic algorithm used by Ethereum (and other blockchains) to ensure that funds can only be spent by their owners.
  • EIP (Ethereum): Stands for “Ethereum Improvement Proposal” (much like BIP on Bitcoin). A design document providing information to the Ethereum community, describing a proposed new feature of its processes or environment. See the list of EIPs here. (See also “ERC”)
  • ENS (Ethereum): Ethereum Name Service. Much like Internet DNS, Ethereum proposes a domain name service for accounts. Instead of referring to an account by the account number, you may use a name (like web pages instead of IP numbers). Check the ENS here.
  • Entropy (General): In the context of cryptography, lack of predictability or level of randomness. When generating secret information, such as private keys, algorithms usually rely on a source of high entropy to ensure the output is unpredictable.
  • EOA (Ethereum): Externally Owned Account. An account created by of for human users of the Ethereum network.
  • ERC (Ethereum): Ethereum Request for Comments. A label is given to some EIPs that attempt to define a specific standard of Ethereum usage.
  • Ethash (Ethereum): A proof-of-work algorithm for Ethereum 1.0. Ethash wiki.
  • Ether (Ethereum): The native cryptocurrency used by the Ethereum ecosystem., which covers gas costs when executing smart contracts. Its symbol is Ξ, the Greek uppercase Xi character.
  • Event (Ethereum): Allows the use of EVM logging facilities. DApps can listen for events and use them to trigger JavaScript callbacks in the user interface. See the docs.
  • EVM (Ethereum): Ethereum Virtual Machine. A stack-based virtual machine that executes bytecode. In Ethereum, the execution model specifies how the system state is altered given a series of bytecode instructions and a small tuple of environmental data. This is specified through a formal model of a virtual state machine. See how it works.
  • EVM Assembly Language (Ethereum): A human-readable form of EVM bytecode.
  • Extra Nonce (Bitcoin): As difficulty increased, miners often cycled through all 4 billion values of the nonce without finding a block. Because the coinbase script can store between 2 and 100 bytes of data, miners started using that space as extra nonce space, allowing them to explore a much larger range of block header values to find valid blocks.
  • Fallback Function (General): A default function called in the absence of data or a declared function name.
  • Faucet (Blockchain/Ethereum): A service that dispenses funds in the form of free test ether (or other crypto depending on the blockchain) that can be used on a testnet. Here’s an ethereum faucet.
  • Fees (Blockchain): In Bitcoin blockchain, the sender of a transaction often includes a fee to the network for processing the requested transaction. Most transactions require a minimum fee of 0.5 mBTC.
  • Finney (Ethereum): A denomination of ether. 10¹⁵ Finney = 1 ether.
  • Fork (general): A change in protocol causing the creation of an alternative chain, or a temporal divergence in two potential block paths during mining. The concept is related to a common software development practice where someone “makes a copy” of the code at some point in time and continue the development outside of the main project.
  • Frontier (Ethereum): The initial test development stage of Ethereum, which lasted from July 2015 to March 2016.
  • Ganache (Ethereum): A personal Ethereum blockchain that you can use to run tests, execute commands, and inspect state while controlling how the chain operates. Download here.
  • Gas (Ethereum): A virtual fuel used in Ethereum to execute smart contracts. The EVM uses an accounting mechanism to measure the consumption of gas and limit the consumption of computing resources (see “Turing complete”). Here’s a gas estimation site.
  • Gas Limit (Ethereum): The maximum amount of gas a transaction or block may consume.
  • Gavin Wood (General): A British programmer who is the co-founder and former CTO of Ethereum. In August 2014 he proposed Solidity, a contract-oriented programming language for writing smart contracts. See other “must-follow” crypto personalities.
  • Genesis Block (Blockchain): The first block in a blockchain, used to initialize a particular network and its cryptocurrency. Here’s bitcoin’s genesis block.
  • Geth (Ethereum): Go Ethereum. One of the most prominent implementations of the Ethereum protocol, written in the Go programming language.
  • Hard Fork (General): A permanent divergence in the blockchain; also known as a hard-forking change. One commonly occurs when nonupgraded nodes can’t validate blocks created by upgraded nodes that follow newer consensus rules. Not to be confused with a fork, soft fork, software fork, or Git fork.
  • Hash (General): A fixed-length fingerprint of variable-size input, produced by a hash function.
  • Hashlocks (Bitcoin): A Hashlock is a type of encumbrance that restricts the spending of output until a specified piece of data is publicly revealed. Hashlocks have the useful property that once any hashlock is opened publicly, any other hashlock, any other hashlock secured using the same key can also be opened. This makes it possible to create multiple outputs that are all encumbered by the same hashlock and which all become spendable at the same time.HD Wallet (blockchain): A wallet using the hierarchical deterministic (HD) key creation and transfer protocol (BIP-32)
  • HD Wallet Seed (Blockchain): A value used to generate the master private key and master chain code or an HD wallet. The wallet seed can be represented by mnemonic words, making it easier for humans to copy, back up, and restore private keys.
  • HD Protocol (Bitcoin): The Hierarchical Deterministic (HD) key creation and transfer protocol (BIP32), which allows creating child keys from parent keys in a hierarchy.
  • HTLC (Bitcoin): A Hashed TimeLock Contract or HTLC is a class of payments that use hashlocks and timelocks to require that the receiver of payment either acknowledge receiving the payment prior to a deadline by generating cryptographic proof of payment or forfeit the ability to claim the payment, returning it to the payer.v
  • Homestead (Ethereum): The second development stage of Ethereum, launched in March 2016 at block #1.150.000
  • HODL, HODLING or HODLER (crypto): More related to the crypto “slang”. This refers to the action of holding your crypto assets to wait for the price to rise over time. The very first time the term HODL appeared on the Bitcoin talk forum was in 2013 and came from a member named GameKyuubi under the thread “I AM HODLING”.
  • Merkle Root (General): The root node of a Merkle tree, a descendant of all the hashed pairs in the tree. In Bitcoin blockchain, block headers must include a valid Merkle root descended from all transactions in that block.
  • Message (Ethereum): An internal transaction that is never serialized and only sent within the EVM.
  • Message Call (Ethereum): The act of passing a message from one account to another. If the destination account is associated with EVM code, then the VM will be started with the state of that object and the message acted upon.
  • Mempool (Bitcoin): The bitcoin Mempool (memory pool) is a collection of all transaction data in a block that has been verified by bitcoin nodes, but are not yet confirmed. See the mempool size here. For a better understanding of bitcoin metrics, see this post.
  • Metropolis (Ethereum): The third development stage of Ethereum, launched in October 2017.
  • Miner (Blockchain): A network node that finds valid proof of work for new blocks, by repeated hashing. See my blog post on Blockchain nodes for more info.
  • Mist (Ethereum): The first Ethereum-enabled browser, built by the Ethereum Foundation. It contains a browser-based wallet that was the first implementation of the ERC20 token standard (Fabian Vogelsteller, author of ERC20, was also the main developer of Mist). Mist was also the first wallet to introduce the camelCase checksum. Mist runs a full node and offers a full DApp browser with support for Swarm-based storage and ENS addresses.
  • Multisignature (Bitcoin): Multisignature (multisig) refers to requiring more than one key to authorize a bitcoin transaction.
  • NFT (Ethereum): Stands for Non-fungible Token (also known as “deed”). This is a token standard introduced by the ERC721 proposal. NFTs can be tracked and traded, but each token is unique and distinct; they are not interchangeable like ERC20 tokens. NFTs can represent ownership of digital or physical assets.
  • Node (General/Blockchain): A software client that participates in a network.
  • Nonce (Blockchain): In cryptography, a value that can only be used once. On the Ethereum environment, there are two types of nonce; an account nonce is a transaction counter in each account, which is used to prevent replay attacks; a proof-of-work (aka PoW) nonce is the random value in a block that was used to satisfy the PoW. A PoW nonce is also used in the Bitcoin Blockchain.
  • Off-Chain-Transactions (Blockchain): An off-chain transaction is the movement of value outside of the blockchain. While an on-chain transaction — usually referred to as simply transaction — modifies the blockchain and depends on the blockchain to determine it’s validity an off-chain transaction relies on other methods to record and validate the transaction.
  • Opcode (Bitcoin): Operation codes from the Bitcoin Script Language which push data or perform functions within a pubkey script or signature script.
  • Open Assets Protocol (Bitcoin): The Open Assets Protocol is a simple and powerful protocol built on top of the bitcoin blockchain. It allows issuance and transfer of user-created assets. The Open Assets protocol is an evolution of the concept of colored coins.
  • OP_RETURN (Bitcoin): An opcode used in one of the outputs in an OP_RETURN transaction. Not to be confused with OP_RETURN transaction.
  • OP_RETURN Transaction (Bitcoin): A transaction type relayed and mined by default in Bitcoin Core 0.9.0 and later that adds arbitrary data to a provably unspendable pubkey script that full nodes don’t have to store in their UTXO database. Not to be confused with OP_RETURN opcode.
  • Orphan Block (bitcoin): Blocks whose parent block has not been processed by the local node, so they can’t be fully validated yet. See the orphaned blocks in bitcoin here.
  • Orphan Transactions (Bitcoin): Transactions that cant go into the pool due to one or more missing input transactions.
  • Output (Bitcoin): Output, transaction output, or TxOut is an output in a transaction which contains two fields: a value field for transferring zero or more satoshis and a pubkey script for indicating what conditions must be fulfilled for those satoshis to be further spent.
  • Ommer (Blockchain): A child block of an ancestor that is not itself an ancestor. When a miner finds a valid block, another miner may have published a competing block which is added to the tip of the blockchain. Unlike with Bitcoin, orphaned blocks in Ethereum can be included by newer blocks as ommers and receive a partial block reward. The term “ommer” is the preferred gender-neutral term of the sibling of a parent node, but this is also sometimes referred to as an “uncle”.
  • Parity (Ethereum): One of the most prominent interoperable implementations of the Ethereum client software.
  • Private Key (General): The secret number that allows users of a blockchain to prove ownership of an account or contracts, by producing a digital signature (see “public key,” “address,” “ECDSA”).
  • Proof-of-Stake (Blockchain) (PoS): A method by which a cryptocurrency blockchain protocol aims to achieve distributed consensus. PoS asks users to prove ownership of a certain amount of cryptocurrency (their “stake” in the network) in order to be able to participate in the validations of transactions.
  • Proof-of-Work (Blockchain) (PoW): A piece of data (the proof) that requires significant computation to find. In Ethereum, miners must find a numeric solution to the Ethash algorithm that meets a network-wide difficulty target. The same thing applies for Bitcoin except that Bitcoin uses the SHA-256.
  • Public Key (General): A number, derived via a one-way function from a private key, which can be shared publicly and used by anyone to verify a digital signature made with the corresponding private key.
  • P2PKH (Bitcoin): Transactions that pay a bitcoin address to contain P2PKH or Pay To PubKey Hash scripts. An output locked by a P2PKH script can be unlocked (spent) by presenting a public key and a digital signature created by the corresponding private key.
  • P2SH (Bitcoin): PS2H or Pay-to-Script-Hash is a powerful new type of transaction that greatly simplifies the use of complex transaction scripts. With P2SH the complex script that details the conditions for spending the output (redeem script) is not presented in the locking script. Instead, only a hash of it is in the locking script.
  • PS2H address (Bitcoin): P2SH addresses are Base58Check encodings of the 20-byte hash of a script, PS2H addresses use the version prefix “5”, which results in Base58Check-encoded addresses that start with a “3”. P2SH addresses hide all of the complexity so that the person making a payment does not see the script.
  • P2WPKH (Bitcoin): P2WPKH stands for “Pay-To-Witness-Public-Key-Hash”. The signature of this hash contains the same information as P2PKH spending but is located in the witness field (inside the block header) instead of the scriptSig field. The scriptPubKey is also modified.
  • P2WSH (Bitcoin): The difference between P2SH and P2WSH is about the cryptographic proof of location change from the scriptSig field to the witness field and the scriptPubKey that is also modified.
  • Paper Wallet (Blockchain): In the most specific sense, a paper wallet is a document containing all of the data necessary to generate any number of Bitcoin private keys, forming a wallet of keys. However, people often use the term to mean any way of storing bitcoins offline as a physical document. This second definition also includes paper keys and redeemable codes. See more about crypto wallets here.
  • Payment Channels (Bitcoin): A micropayment channel or payment channel is a class of techniques designed to allow users to make multiple bitcoin transactions without committing all of the transactions to the bitcoin blockchain. In a typical payment channel, only two transactions are added to the blockchain but an unlimited or nearly unlimited number of payments can be made between the participants. Check out this amazing blog post on Payment Channels
  • Pooled Mining (Blockchain): Pooled mining is a mining approach where multiple generating clients contribute to the generation of a block and then split the block reward according to the contributed processing power.
  • Receipt (Ethereum): Data returned by an Ethereum client to represent the result of a particular transaction, including a hash of the transaction, its block number, the amount of gas used, and, in case of deployment of a smart contract, the address of the contract.
  • Re-entrancy Attack (Ethereum): An attack that consists of an attacker contract calling a victim contract function in such a way that during execution the victim calls the attacker contract again, recursively. This can result, for example, in the theft of funds by skipping parts of the victim contract that update balances or count withdrawal amounts
  • Reward (Blockchain): An amount of ether included in each new block as a reward by the network to the miner who found the proof-of-work solution.
  • RLP (Ethereum): Recursive Length Prefix. An encoding standard designed by the Ethereum developers to encode and serialize objects (data structures) of arbitrary complexity and length.
  • RIPEMD-160 (general): RIPEMD-160 is a 160-bit cryptographic hash function. RIPEMD-160 is a strengthened version of RIPEMD with a 160-bit hash result and is expected to be secure for the next ten years or more.
  • Satoshi Nakamoto (Blockchain): The name used by the person or people who designed Bitcoin, created its original reference implementation and were the first to solve the double-spend problem for digital currency. Their real identity remains unknown.
  • Satoshi (Bitcoin): A satoshi is the smallest denomination of bitcoin that can be recorded on the blockchain. It is the equivalent of 0.00000001 bitcoin and is named after the creator of Bitcoin, Satoshi Nakamoto.
  • Script (general): In Software programming jargon, is usually referred to as a piece of code that execute certain actions. It is also the programming language on which Bitcoin is written. Bitcoin uses a scripting system for transactions. Forth-like, Script is simple, stack-based, and processed from left to right. It is purposefully not Turing-complete, with no loops.
  • ScriptPubKey (Bitcoin’s Pubkey Script): ScriptPubKey or pubkey script, is a script included in outputs which set the conditions that must be fulfilled or those satoshis to be spent. Data for fulfilling the conditions can be provided in a signature script.
  • ScriptSig (Bitcoin’s Signature Script): ScriptSig or signature scripts, is the data generated by a spender which is almost always used as variables to satisfy a pubkey script.
  • Segregated Witness (Bitcoin): Segregated Witness is a proposed upgrade to the Bitcoin protocol which technological innovation separates signature data from bitcoin transactions. Segregated Witness is a proposed fork; a change that technically makes Bitcoin’s protocol rules more restrictive.
  • Serenity (Ethereum): The fourth and final development stage of Ethereum. Serenity does not yet have a planned release date.
  • Serpent (General): A procedural (imperative) smart contract programming language with syntax similar to Python
  • SHA (General): Stands for Secure Hash Algorithm. A family of cryptographic hash functions published by the National Institute of Standards and Technology (NIST).
  • Singleton (General): A computer programming term that describes an object of which only a single instance can exist.
  • SPV (Bitcoin): SPV stands for “Simplified Payment Verification”, and is a method for verifying particular transactions were included in a block without downloading the entire block. The method is used by some lightweight Bitcoin clients.
  • Smart Contract (Blockchain/Ethereum): A program that executes on the Ethereum computing infrastructure.
  • Solidity (Ethereum): A procedural (imperative) programming language with a syntax that is similar to JavaScript, C++, or Java. The most popular and most frequently used language for Ethereum smart contracts.
  • Solidity Inline Assembly (Ethereum): EVM assembly language in Solidity program. Solidity’s support for inline assembly makes it easier to write certain operations
  • Soft Fork (General): Soft fork or soft-forking change, is a temporary fork in the blockchain which commonly occurs when miners using non-upgrades nodes don’t follow a new consensus rule their nodes don’t know about. Not to be confused with fork, hard fork, software fork or Git fork.
  • Stale Block (Blockchain): A Block which were successfully mined but which isn’t included in the current best blockchain, likely because some other block at the same height had its chain extended first.
  • Spurious Dragon (Ethereum): A hard fork of the Ethereum blockchain, which occurred at block #2,675,000 to address more denial-of-service attack vectors and clear state (see also “Tangerine Whistle”). Also, a replay attack protection mechanism.
  • Swarm (Blockchain): A decentralized (P2P) storage network, used along with Web3 and Whisper to build DApps.
  • Szabo (Ethereum): A denomination of ether. 10 ¹² Szabo = 1 ether
  • Tangerine Whistle (Ethereum): A hard fork of the Ethereum blockchain, which occurred at block #2,463,000 to change the gas calculation for certain I/O-intensive operations and to clear the accumulated state from a denial-of-service attack, which exploited the low gas cost of those operations.
  • Testnet (Blockchain): Short for “test network,” a network used to simulate the behavior of the main blockchain network.
  • Timelocks (Bitcoin): A Timelock is a type of encumbrance that restricts the spending of some bitcoin until a specified future time or block height. Timelocks feature prominently in many Bitcoin contracts, including payment channels and hashed timelock contracts.
  • To the Moon, or 2TMoon, or Mooning (Crypto): Usually related to the crypto “slang”. Used to express a very optimistic view of the potential price of a cryptocurrency.
  • Transaction (Blockchain): Data committed to the Blockchain signed by an originating account targeting a specific address. The transaction contains metadata (e.g. In Ethereum contains the gas limit for that transaction)
  • Transaction Pool (Blockchain): An unordered collection of transactions that are not in blocks in the main chain, but for which we have input transactions. See the Bitcoin live unconfirmed transactions here.
  • Truffle (Ethereum): One of the most commonly used Ethereum development frameworks.
  • Turing complete (Blockchain): A concept named after English mathematician and computer scientist Alan Turing: a system of data-manipulation rules (such as a computer’s instruction set, a programming language, or a cellular automaton) is said to be “Turing complete” or “computationally universal” if it can be used to simulate any Turing machine.
  • UTXO (Bitcoin): Stands for “Unspent Transaction Output”. UTXO is an unspent transaction output that can be spent as an input in a new transaction. The UTXO is one of the most important building blocks for Bitcoin transactions. Learn more about Bitcoin transactions here.
  • Vitalik Buterin (Ethereum): A Russian-Canadian programmer and writer primarily known as the co-founder of Ethereum and of Bitcoin Magazine. Follow him on Twitter.
  • Vyper (General): A high-level programming language, similar to Serpent, with Python-like syntax. Intended to get closer to a pure functional language. Created by Vitalik Buterin.
  • Wallet (Blockchain): Software that holds secret keys. Used to access and control Ethereum accounts and interact with smart contracts. Keys need not be stored in a wallet, and can instead be retrieved from offline storage (e.g., a memory card or paper) for improved security. Despite the name, wallets never store the actual coins or tokens.
  • WIF (Blockchain): Stands or “Wallet Import Format”. WIF is a data interchange format designed to allow exporting and importing a single private key with a flag indicating whether or not it uses a compressed public key.
  • Web3 (General): The third version of the web. First proposed by Dr. Gavin Wood, Web3 represents a new vision and focus for web applications: from centrally owned and managed applications, to applications built on decentralized protocols.
  • Wei (Ethereum): The smallest denomination of ether. 10¹⁸ wei = 1 ether.
  • Whisper (General): A decentralized (P2P) messaging service. It is used along with Web3 and Swarm to build DApps.
  • Zero Address (Ethereum): A special Ethereum address, composed entirely of zeros, that is specified as the destination address of a contract creatioºn transaction.