// REFERENCE

Crypto Glossary

Plain-English definitions for the terms you’ll encounter in Bitcoin and crypto — no jargon, no fluff.

Address: A string of letters and numbers that represents a destination on a blockchain — like an email address for receiving crypto. Bitcoin addresses typically start with “1”, “3”, or “bc1”. You can share your address publicly; it’s derived from your public key. See also: Bitcoin Wallet Guide.
Altcoin: Any cryptocurrency other than Bitcoin. “Alt” is short for alternative. Ethereum, Solana, XRP, and thousands of other tokens are all altcoins. The term is sometimes used dismissively, but many altcoins are serious projects with distinct technology.
ATH (All-Time High): The highest price a cryptocurrency has ever reached. Bitcoin’s ATH as of early 2024 was approximately $73,750. Often used in phrases like “Bitcoin is trading at 80% of its ATH.”
Bitcoin (BTC): The first and largest cryptocurrency by market cap, created by the pseudonymous Satoshi Nakamoto in 2009. Bitcoin is a decentralized digital currency with a fixed supply of 21 million coins, secured by a proof-of-work consensus mechanism.
Block: A bundle of transaction data recorded on the blockchain. Bitcoin produces roughly one block every 10 minutes; each block contains a batch of confirmed transactions, a reference to the previous block, and the miner’s proof of work. See: What Is Bitcoin Mining?
Block reward: The amount of newly minted Bitcoin a miner receives for successfully adding a block to the blockchain. The reward started at 50 BTC in 2009 and is cut in half every 210,000 blocks in an event called the halving. As of 2024, the reward is 3.125 BTC. See: The Bitcoin Halving Explained.
Blockchain: A public, append-only ledger of all transactions on a network. Each “block” of data is cryptographically linked to the one before it, forming a chain. Once a record is added it is practically impossible to alter without redoing all subsequent work — which is what makes it tamper-resistant.
Bridge: A protocol that lets you move cryptocurrency between two different blockchain networks. For example, bridging ETH from Ethereum mainnet to the Arbitrum Layer 2. Bridges have historically been targets of hacks — always use well-established ones and verify the URL carefully.
Cold wallet (cold storage): A wallet whose private keys are stored completely offline, disconnected from the internet. The most common form is a hardware wallet (Ledger, Trezor). Cold storage is the gold standard for securing large crypto holdings. See: What Is a Bitcoin Wallet?
Consensus mechanism: The rules a blockchain uses to agree on which transactions are valid without a central authority. Bitcoin uses Proof of Work; Ethereum uses Proof of Stake. Different mechanisms have different trade-offs in security, energy use, and decentralization.
Custody / custodial: When a third party (like a crypto exchange) holds your private keys on your behalf, it’s called custodial. Coinbase, Kraken, and other exchanges are custodians. Non-custodial means you hold your own keys. “Not your keys, not your coins” refers to custodial risk.
DCA (Dollar-Cost Averaging): An investing strategy where you buy a fixed dollar amount of an asset on a regular schedule (e.g., $100 of Bitcoin every week), regardless of the price. DCA removes the stress of trying to time the market. See: What Is Dollar-Cost Averaging?
DeFi (Decentralized Finance): Financial services — lending, borrowing, trading, earning yield — built on smart contracts rather than banks or brokerages. DeFi protocols run on blockchains (primarily Ethereum) and operate without a central company. See: What Is DeFi?
DEX (Decentralized Exchange): A trading platform that operates via smart contracts rather than a central company. Users trade directly from their own wallets. Examples include Uniswap, Curve, and dYdX. Unlike centralized exchanges (Coinbase, Kraken), DEXs don’t require KYC or hold customer funds.
Difficulty adjustment: Bitcoin automatically adjusts how hard it is to mine a block every 2016 blocks (~2 weeks) to keep average block time near 10 minutes. If more miners join, difficulty rises; if miners leave, it drops. This self-correcting mechanism ensures Bitcoin’s block schedule stays predictable.
ETF (Exchange-Traded Fund): A financial product that tracks an underlying asset and trades on a stock exchange. Bitcoin spot ETFs — approved in the US in January 2024 — let investors gain Bitcoin exposure through a traditional brokerage without managing crypto directly. See: What Is a Bitcoin ETF?
Ethereum (ETH): The second-largest cryptocurrency and the leading smart contract platform. Ethereum introduced programmable money — code that executes automatically without a middleman. It’s the foundation for most DeFi, NFTs, and Layer 2 networks. See: Bitcoin vs. Ethereum.
Fiat currency: Government-issued money with no intrinsic backing — its value comes from government decree and trust. US dollars, euros, and yen are fiat currencies. Bitcoin was explicitly designed as an alternative to fiat that can’t be inflated by any central authority.
FOMO (Fear Of Missing Out): The anxiety that drives investors to buy an asset after a big price run-up because they fear missing further gains. FOMO buying near market peaks is one of the most common ways retail investors lose money in crypto. It’s the opposite of rational, disciplined investing.
FUD (Fear, Uncertainty, Doubt): Negative, often misleading information spread about a cryptocurrency or project — sometimes by competitors, short-sellers, or regulators — that causes prices to fall. Conversely, dismissing all criticism as “FUD” is also a red flag; not all bad news is a conspiracy.
Gas / Gas fee: The fee paid to use the Ethereum network. Gas measures the computational effort required by a transaction or smart contract. Fees are denominated in gwei (billionths of ETH) and fluctuate with network demand. See: What Are Gas Fees?
Gwei: One billionth of an Ether (0.000000001 ETH). Gas prices on Ethereum are quoted in gwei. When the network is quiet, gas might be 5–15 gwei; during peak congestion it has exceeded 500 gwei.
Halving: A pre-programmed event in Bitcoin’s code that cuts the block reward in half every 210,000 blocks (~4 years). The 2024 halving reduced the reward from 6.25 to 3.125 BTC. The halving controls Bitcoin’s supply schedule and is central to the argument for Bitcoin as a scarce asset. See: The Bitcoin Halving Explained.
Hard fork: A permanent change to a blockchain’s rules that is not backwards-compatible — nodes that don’t upgrade are incompatible with the new chain. Hard forks can split a blockchain into two (as happened when Bitcoin Cash split from Bitcoin in 2017). Contrast with a soft fork, which is backwards-compatible.
Hash rate: The total computational power being used to mine and secure a blockchain. Bitcoin’s hash rate is measured in exahashes per second (EH/s). A higher hash rate means a more secure network — it would require more energy and hardware to mount a 51% attack.
HODL: Crypto slang for “hold” — originating from a typo in a 2013 Bitcoin forum post — meaning to hold your cryptocurrency rather than sell during market volatility. The philosophy is that long-term holders have historically outperformed traders. “HODL” became a meme and investing ethos.
Hot wallet: A wallet whose private keys are stored on an internet-connected device — a mobile app, browser extension, or desktop program. Hot wallets are convenient for frequent use but more vulnerable to hacks than cold storage. Fine for amounts you’d carry as cash; not for life savings. See: What Is a Bitcoin Wallet?
KYC (Know Your Customer): The identity verification process required by regulated financial institutions, including crypto exchanges. US law requires exchanges to verify customer identities (name, address, government ID) to prevent money laundering and fraud. Providing accurate KYC information is a legal requirement on regulated platforms.
Layer 2 (L2): A secondary network built on top of a base blockchain (Layer 1) that processes transactions more cheaply and quickly, then settles the final state back to the main chain. Arbitrum, Optimism, and Base are Ethereum L2s. The Lightning Network is Bitcoin’s L2. See: What Are Gas Fees?
Liquidity: How easily an asset can be bought or sold without significantly moving its price. Bitcoin and Ethereum are highly liquid — you can buy or sell millions of dollars without much price impact. Smaller altcoins often have low liquidity, meaning large orders can move prices dramatically.
Market cap (Market capitalization): The total value of all coins in circulation: current price × circulating supply. Bitcoin’s market cap is the most common measure of its size relative to other cryptocurrencies. A $1 trillion market cap means all existing Bitcoin is worth $1 trillion at current prices.
Mempool: Short for “memory pool” — the waiting room for unconfirmed transactions on a blockchain. When you send a transaction, it sits in the mempool until a miner or validator includes it in a block. When the mempool is full, fees rise; when it empties, fees fall.
Mining: The process of validating Bitcoin transactions and adding them to the blockchain by solving a computationally intensive mathematical puzzle (proof of work). Miners who succeed earn the block reward. Mining requires significant hardware and energy. See: What Is Bitcoin Mining?
NFT (Non-Fungible Token): A unique digital token on a blockchain that represents ownership of a specific item — digital art, a collectible, a game item, or real-world asset. Unlike Bitcoin (where one BTC equals any other BTC), each NFT is unique and not interchangeable. Most NFTs live on Ethereum or Solana.
Node: A computer that participates in a blockchain network by downloading, storing, and validating the blockchain’s data. Running a full node means independently verifying every transaction yourself rather than trusting someone else. Bitcoin has tens of thousands of full nodes globally.
Private key: A secret cryptographic string that proves ownership of a blockchain address and authorizes transactions. Anyone with your private key can spend your funds — it cannot be reset or recovered if lost. Modern wallets derive private keys from a seed phrase rather than displaying them directly. See: What Is a Bitcoin Wallet?
Proof of Stake (PoS): A consensus mechanism where validators lock up (“stake”) their own crypto as collateral to earn the right to validate transactions. Ethereum switched from Proof of Work to Proof of Stake in 2022 (“The Merge”), reducing its energy consumption by over 99%.
Proof of Work (PoW): Bitcoin’s consensus mechanism. Miners compete to solve a cryptographic puzzle; the winner adds the next block and earns the block reward. “Work” = real computational energy expended. This energy cost is what makes Bitcoin’s ledger tamper-resistant. See: What Is Bitcoin Mining?
Public key: The cryptographic counterpart to a private key. Your public key (or the address derived from it) is what others use to send you crypto. You can share it freely — it’s mathematically impossible to reverse-engineer the private key from a public key.
Satoshi (sat): The smallest unit of Bitcoin — one hundred millionth of a BTC (0.00000001 BTC). Named after Bitcoin’s creator, Satoshi Nakamoto. At $60,000/BTC, one satoshi is worth $0.0006. The Lightning Network enables payments measured in single satoshis.
Seed phrase (recovery phrase / mnemonic): A sequence of 12 or 24 ordinary English words that serves as the master backup for a crypto wallet. Your seed phrase mathematically generates every private key in your wallet. Anyone with your seed phrase controls your funds — store it offline, never photograph it or type it into any website. See: What Is a Bitcoin Wallet?
Smart contract: Self-executing code stored on a blockchain that automatically enforces the terms of an agreement when predefined conditions are met — no intermediary required. Smart contracts power DeFi protocols, NFT marketplaces, and DAOs. Ethereum was the first platform to make smart contracts practical at scale.
Stablecoin: A cryptocurrency designed to maintain a stable value, usually pegged to $1. Common types include fiat-backed (USDC, USDT), crypto-backed (DAI), and algorithmic. Stablecoins are widely used in DeFi and for moving money quickly without volatility. See: What Is a Stablecoin?
Token vs. coin: A coin is native to its own blockchain (BTC on Bitcoin, ETH on Ethereum). A token is built on top of an existing blockchain using its smart contract system (USDC, UNI, and LINK are all tokens on Ethereum). In practice the terms are used loosely and interchangeably.
Transaction fee: The fee paid to include a transaction in a block. On Bitcoin, fees are based on transaction size in bytes. On Ethereum, fees are based on computational complexity (gas). Fees go to miners (Bitcoin) or validators (Ethereum) as compensation for processing transactions.
Unrealized gain / loss: The profit or loss on a crypto position you haven’t sold yet. If you bought Bitcoin at $30,000 and it’s now $60,000, you have an unrealized gain of $30,000 per BTC. It only becomes a realized gain — and a taxable event — when you sell. See: Crypto Taxes 101.
Volatility: The degree to which an asset’s price fluctuates over time. Bitcoin is significantly more volatile than stocks or gold — double-digit percentage moves in a single day are not unusual. High volatility creates opportunity for large gains but also for large losses.
Wallet: Software or hardware that stores your cryptographic keys and lets you send and receive cryptocurrency. Despite the name, a wallet doesn’t hold coins — coins live on the blockchain. It holds the keys that prove you own those coins. See: What Is a Bitcoin Wallet?
Whale: An individual or entity that holds a large enough amount of a cryptocurrency to potentially move its price when they buy or sell. In Bitcoin, “whale” typically refers to addresses holding 1,000+ BTC. Whale activity is closely watched by traders.