Glossary
Every term in the Academy, A to Z. Click any entry for the full explanation.
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114 of 114 terms
0-9
- 51% Attack A 51% attack is when a single party controls the majority of a network’s mining power or stake and can rewrite recent history.⛏️ Mining & Consensus
- 51% Attacks (Risk View) From a user’s perspective, a 51% attack risk is the chance that a small network’s recent transactions can be reversed by a majority miner or validator.🛡️ Security & Risks
A
- Account Model In the account model (used by Ethereum), each address has a running balance that transactions increase or decrease.🔁 Transactions
- Altcoins Altcoin is shorthand for any cryptocurrency other than Bitcoin.🪙 Cryptocurrencies & Tokens
- AML (Anti-Money Laundering) AML refers to the laws and monitoring systems designed to stop criminals from disguising illicit funds as legitimate.⚖️ Regulatory & Compliance
- Automated Market Maker (AMM) An AMM is a DEX design that prices trades with a mathematical formula against a liquidity pool instead of matching buyers and sellers.🏦 DeFi (Decentralized Finance)
B
- Bitcoin (BTC) Bitcoin is the first and largest cryptocurrency, launched in 2009 as decentralised digital money with a fixed supply of 21 million.🪙 Cryptocurrencies & Tokens
- Bitcoin Whitepaper (Origins) The Bitcoin whitepaper is a nine-page paper published in 2008 by the pseudonymous Satoshi Nakamoto describing a peer-to-peer electronic cash system.🧭 Foundations
- Block Hash The block hash is the fingerprint of a block’s header and serves as the block’s unique identifier.🧱 Blockchain Core Concepts
- Block Header The block header is the compact summary at the top of a block that gets hashed to produce the block’s identity.🧱 Blockchain Core Concepts
- Block Reward The block reward is the newly created coins plus transaction fees paid to whoever produces a valid block.⛏️ Mining & Consensus
- Block Structure A block is a container holding a header (metadata) and a body (the list of transactions).🧱 Blockchain Core Concepts
- Byzantine Fault Tolerance A Byzantine fault tolerant (BFT) system keeps working correctly even if some participants fail or act maliciously.⛏️ Mining & Consensus
C
- Centralized Exchange (CEX) A centralized exchange is a company that operates a trading venue, holds customer assets in custody and matches buy and sell orders on its own systems.📊 Exchanges & Trading
- Centralized vs Decentralized Systems A centralized system is run by one authority; a decentralized one is run collectively by many independent participants.🧭 Foundations
- Chain of Blocks (Blockchain Linking) Blocks are linked by each one containing the hash of its predecessor, forming an unbroken chain back to the genesis block.🧱 Blockchain Core Concepts
- Circulating Supply vs Total Supply Circulating supply is the number of coins currently tradable; total supply includes coins that exist but are locked, and max supply is the hard cap that can ever exist.📈 Market Concepts
- Coins vs Tokens A coin is the native asset of its own blockchain; a token is an asset created by a smart contract on someone else’s blockchain.🪙 Cryptocurrencies & Tokens
- Confirmations A confirmation is each new block added after the block that contains your transaction.🔁 Transactions
- Consensus Mechanism A consensus mechanism is the rule set a network uses to decide which participant adds the next block and which chain is the true one.⛏️ Mining & Consensus
- Cross-chain Bridges A bridge lets you move an asset from one blockchain to another, typically by locking it on the source chain and minting a wrapped version on the destination.📜 Smart Contracts & Ethereum
- Crypto Regulations (Global Overview) Crypto regulation is the patchwork of national laws deciding how digital assets are classified, taxed and traded.⚖️ Regulatory & Compliance
- Crypto Wallets A crypto wallet is software or hardware that stores your keys and lets you sign transactions; the coins themselves stay on the blockchain.👛 Wallets & Keys
- Cryptography Fundamentals Cryptography is the science of protecting information so that only intended parties can read or verify it.🔐 Cryptography Basics
- Custodial vs Non-Custodial Wallets In a custodial wallet a third party (like an exchange) holds your keys; in a non-custodial wallet only you do.👛 Wallets & Keys
D
- DAOs (Decentralized Autonomous Organizations) A DAO is an organisation governed by token-holder votes and smart contracts rather than executives and a board.🖼️ NFTs & Web3
- Decentralization Decentralization is the spreading of control across many independent participants so that no single entity can dictate outcomes.🧱 Blockchain Core Concepts
- Decentralized Applications (DApps) A DApp is an application whose back-end logic runs on smart contracts instead of a company’s servers.📜 Smart Contracts & Ethereum
- Decentralized Exchange (DEX) A DEX is a set of smart contracts that lets users trade directly from their own wallets without a custodian.📊 Exchanges & Trading
- Delegated Proof of Stake (DPoS) DPoS lets token holders vote for a small set of delegates who produce blocks on everyone’s behalf.⛏️ Mining & Consensus
- Difficulty Adjustment Difficulty adjustment automatically tunes how hard the mining puzzle is so blocks keep arriving at the intended pace.⛏️ Mining & Consensus
- Digital Signatures A digital signature is cryptographic proof that a message was approved by the holder of a specific private key and has not been changed.🔐 Cryptography Basics
- Distributed Consensus Distributed consensus is how independent nodes agree on a single version of the ledger without a central referee.🧱 Blockchain Core Concepts
- Distributed Ledger Technology (DLT) DLT is any system where a ledger is replicated and kept in sync across many independent computers.🧭 Foundations
- Double Spending Problem Double spending is the risk that the same digital coin is spent twice; blockchains exist largely to prevent it.🔁 Transactions
E
F
G
- Gas & Gas Limit Gas measures the computational work a transaction requires; the gas limit is the maximum you are willing to spend on it.📜 Smart Contracts & Ethereum
- Genesis Block The genesis block is the very first block of a blockchain, hard-coded into the software rather than mined by the network.🧱 Blockchain Core Concepts
- Governance Tokens A governance token gives holders voting rights over a protocol’s decisions, such as fee changes or treasury spending.🪙 Cryptocurrencies & Tokens
H
- Halving A halving is the scheduled event, roughly every four years, when Bitcoin’s new-coin block reward is cut in half.⛏️ Mining & Consensus
- Hardware Wallets A hardware wallet is a small physical device that stores private keys in a secure chip and signs transactions without exposing them.👛 Wallets & Keys
- Hash Functions A hash function turns any input into a fixed-length string of characters that acts like a digital fingerprint.🔐 Cryptography Basics
- Hashing (SHA-256) SHA-256 is the specific hash function Bitcoin uses; it always produces a 256-bit (64 hex character) output.🔐 Cryptography Basics
- Hierarchical Deterministic (HD) Wallets An HD wallet derives an unlimited tree of keys and addresses from a single seed in a predictable way.👛 Wallets & Keys
- Hot Wallet vs Cold Wallet A hot wallet is connected to the internet; a cold wallet keeps keys entirely offline.👛 Wallets & Keys
I
- ICO / IDO / IEO ICOs, IDOs and IEOs are ways new tokens are first sold to the public — directly by the project, on a DEX, or through an exchange, respectively.📈 Market Concepts
- Immutability Immutability means that once data is recorded on the blockchain it is practically impossible to alter or delete.🧱 Blockchain Core Concepts
- Impermanent Loss Impermanent loss is the value a liquidity provider gives up, compared to simply holding, when the two pooled tokens change price relative to each other.🏦 DeFi (Decentralized Finance)
- Interoperability Interoperability is the ability of different blockchains to exchange assets and information with each other.🛰️ Network & Scaling
K
- KYC (Know Your Customer) KYC is the process by which a financial platform verifies who its customers are before letting them transact.⚖️ Regulatory & Compliance
- KYC & AML in Crypto KYC (Know Your Customer) and AML (Anti-Money Laundering) are the identity and monitoring controls regulated crypto platforms must apply to their users.🛡️ Security & Risks
L
- Layer 1 vs Layer 2 A Layer 1 is a base blockchain (Bitcoin, Ethereum); a Layer 2 is a network built on top of it that processes transactions faster and cheaper, then settles back to the base layer.🛰️ Network & Scaling
- Ledger A ledger is the record of all transactions; on a blockchain it is public, append-only and shared by every node.🧱 Blockchain Core Concepts
- Lending & Borrowing Protocols DeFi lending protocols let users deposit crypto to earn interest and borrow against their deposits, all governed by smart contracts.🏦 DeFi (Decentralized Finance)
- Light Clients & SPV Simplified Payment Verification (SPV) is the technique light clients use to confirm a transaction using only block headers and a Merkle proof.🧱 Blockchain Core Concepts
- Liquidity & Liquidity Pools Liquidity is how easily an asset can be bought or sold without moving its price; a liquidity pool is a smart contract holding paired tokens that traders swap against.📊 Exchanges & Trading
- Liquidity Mining Liquidity mining rewards users with a protocol’s own tokens for depositing assets into its liquidity pools.🏦 DeFi (Decentralized Finance)
M
- Mainnet vs Testnet Mainnet is the live blockchain where real value moves; a testnet is a parallel copy with worthless coins used for development and testing.🛰️ Network & Scaling
- Margin & Leverage Margin is the collateral you post to open a leveraged position; leverage multiplies your exposure relative to that collateral.📊 Exchanges & Trading
- Market Cap Market capitalisation is the total value of a cryptocurrency: current price multiplied by circulating supply.📈 Market Concepts
- Market Maker vs Market Taker A maker places an order that waits in the book; a taker fills an existing order immediately.📊 Exchanges & Trading
- Mempool The mempool is each node’s waiting room of valid transactions that have been broadcast but not yet included in a block.🔁 Transactions
- Merkle Trees A Merkle tree hashes transactions in pairs, level by level, until one "root" hash summarises them all.🔐 Cryptography Basics
- Metadata & Tokenization Tokenization is representing an asset as a blockchain token; metadata is the descriptive data (name, image, attributes) attached to that token.🖼️ NFTs & Web3
- Miners & Validators Miners produce blocks on Proof of Work chains; validators do the equivalent job on Proof of Stake chains.⛏️ Mining & Consensus
- Mining Mining is the process of bundling transactions into a block and solving the Proof of Work puzzle to add it to the chain.⛏️ Mining & Consensus
N
- Native Tokens vs ERC Tokens A native token pays for a blockchain’s own fees (ETH on Ethereum); ERC tokens are contract-based assets that ride on top and need the native token for gas.🪙 Cryptocurrencies & Tokens
- Nodes A node is any computer running the network’s software and participating in validating and relaying data.🧱 Blockchain Core Concepts
- Non-Fungible Tokens (NFTs) An NFT is a blockchain token that is one-of-a-kind, used to represent ownership of a specific digital or physical item.🖼️ NFTs & Web3
- Nonce A nonce is a "number used once": a counter on account-based chains, and the value miners vary while searching for a valid block hash.🔁 Transactions
O
- Oracles An oracle is a service that brings real-world data — like prices or weather — onto the blockchain for smart contracts to use.📜 Smart Contracts & Ethereum
- Order Book An order book is the live list of all open buy (bid) and sell (ask) orders for an asset, sorted by price.📊 Exchanges & Trading
- OTC (Over-The-Counter) Trading OTC trading is a direct, privately negotiated trade between two parties, off the public order book.📊 Exchanges & Trading
P
- Paper Wallets A paper wallet is a private key (or seed phrase) printed or written on paper and stored offline.👛 Wallets & Keys
- Peer-to-Peer Networks A peer-to-peer (P2P) network is one where computers talk directly to each other rather than through a central server.🧭 Foundations
- Private Key Management Private key management is the set of practices for generating, storing and backing up the keys that control your funds.👛 Wallets & Keys
- Private Key Theft / Phishing Phishing tricks you into revealing your seed phrase or signing a malicious transaction, giving an attacker control of your funds.🛡️ Security & Risks
- Proof of Stake (PoS) Proof of Stake selects block producers based on the coins they have locked up ("staked") rather than computing power.⛏️ Mining & Consensus
- Proof of Work (PoW) Proof of Work has participants compete to solve a computational puzzle; the winner adds the next block and earns a reward.⛏️ Mining & Consensus
- Public Address A public address is the shareable string, derived from your public key, that others use to send you crypto.👛 Wallets & Keys
- Public Key & Private Key A private key is a secret number that controls your funds; the public key is derived from it and can be shared safely.🔐 Cryptography Basics
R
- Rollups (Optimistic & ZK) A rollup executes transactions off-chain and posts compressed data plus a proof to the main chain, which secures it.🛰️ Network & Scaling
- Rug Pulls A rug pull is when a project’s creators abruptly drain the liquidity or treasury and disappear, leaving holders with worthless tokens.🛡️ Security & Risks
S
- Security Tokens A security token represents ownership in a real asset — equity, debt or revenue — and is regulated like a traditional security.🪙 Cryptocurrencies & Tokens
- Seed Phrase / Mnemonic Phrase A seed phrase is a list of 12 or 24 ordinary words that encodes the master key from which all your wallet’s keys are derived.👛 Wallets & Keys
- Sharding Sharding splits a blockchain’s data and workload into parallel pieces ("shards") so nodes only process a portion of the total.🛰️ Network & Scaling
- Sidechains A sidechain is a separate blockchain connected to a main chain by a bridge, with its own consensus and security.🛰️ Network & Scaling
- Slippage Slippage is the difference between the price you expected and the price your trade actually filled at.📊 Exchanges & Trading
- Smart Contract Vulnerabilities A smart contract vulnerability is a bug in on-chain code that lets an attacker drain funds or break a protocol’s logic.🛡️ Security & Risks
- Smart Contracts A smart contract is a program stored on a blockchain that runs automatically when its conditions are met.📜 Smart Contracts & Ethereum
- Solidity (Overview) Solidity is the most widely used programming language for writing Ethereum smart contracts.📜 Smart Contracts & Ethereum
- Spot Trading vs Futures Trading Spot trading buys or sells the actual asset for immediate delivery; futures trading buys or sells a contract about the asset’s future price.📊 Exchanges & Trading
- Stablecoins A stablecoin is a crypto token designed to hold a steady value, usually pegged 1:1 to a currency like the US dollar.🪙 Cryptocurrencies & Tokens
- Staking Staking is locking up coins to help secure a Proof of Stake network in exchange for rewards.⛏️ Mining & Consensus
- Staking Pools A staking pool combines many users’ coins to run validators together, sharing rewards proportionally.🏦 DeFi (Decentralized Finance)
- Symmetric vs Asymmetric Encryption Symmetric encryption uses one shared key to lock and unlock data; asymmetric encryption uses a linked pair — one public, one private.🔐 Cryptography Basics
T
- Taxation on Crypto Crypto taxation is how gains, income and transfers of digital assets are taxed; rules vary by country and change often.⚖️ Regulatory & Compliance
- Token Standards (ERC-20, ERC-721, ERC-1155, BEP-20) A token standard is a shared blueprint defining how a token behaves so wallets and exchanges can support it automatically.🪙 Cryptocurrencies & Tokens
- Tokenomics Tokenomics is the economic design of a token: supply, issuance, distribution, utility and incentives.📈 Market Concepts
- Transaction (What is a Transaction) A transaction is a signed instruction to move value from one address to another, broadcast to the network for inclusion in a block.🔁 Transactions
- Transaction Fees / Gas Fees A transaction fee is the payment to miners or validators for including your transaction in a block; on Ethereum it is called gas.🔁 Transactions
- Transaction Hash (TXID) A transaction hash, or TXID, is the unique fingerprint of a transaction used to look it up on the blockchain.🔁 Transactions
- Travel Rule The Travel Rule requires exchanges to share sender and receiver identity information with each other when transferring crypto above a threshold.⚖️ Regulatory & Compliance
U
V
W
- Wallet Security Best Practices Wallet security best practices are the everyday habits that keep your keys and accounts out of attackers’ hands.🛡️ Security & Risks
- Web3 Overview Web3 is the vision of an internet where users own their data, identity and assets through blockchain-based wallets rather than platform accounts.🖼️ NFTs & Web3
- What is Blockchain A blockchain is a shared database where records are grouped into blocks and each block is cryptographically linked to the one before it.🧭 Foundations
- What is Cryptocurrency Cryptocurrency is digital money secured by cryptography and recorded on a shared public ledger instead of at a bank.🧭 Foundations
- What is DeFi DeFi is a set of financial services — trading, lending, borrowing, earning — built from smart contracts that anyone can use without an intermediary.🏦 DeFi (Decentralized Finance)
- What is Money (History of Money) Money is anything a society agrees to accept as payment and as a way to store value over time.🧭 Foundations