Bitcoin Glossary — Key Terms Explained Simply
This glossary is designed for absolute beginners. Technical terms are explained in plain English with practical examples.
A
Address (Bitcoin Address)
A string of letters and numbers (like 1A1zP1eP5QGefi2DMPTfTL5SLmv7DivfNa) that you share to receive Bitcoin. Think of it like an email address for money. Each address is derived from your public key.
ASIC (Application-Specific Integrated Circuit)
Specialized computers designed exclusively for Bitcoin mining. They’re thousands of times more efficient than regular computers at solving the mining puzzle. Modern mining is impossible without them. (See Part 3.)
Altcoin
Any cryptocurrency other than Bitcoin. “Alternative coin.” Ethereum, Litecoin, Dogecoin are all altcoins.
B
Block
A batch of Bitcoin transactions that have been verified and added to the blockchain. A new block is created approximately every 10 minutes. (See Part 2.)
Blockchain
A public, chronological ledger of all Bitcoin transactions. Think of it like a shared spreadsheet that everyone can see but no one can edit retroactively. Each new “page” (block) links to the previous one, forming a chain. (See Part 2.)
Block Reward
The amount of new Bitcoin awarded to a miner who successfully adds a block to the chain. Started at 50 BTC per block (2009), currently 3.125 BTC after four halvings. (See Part 3 & 4.)
C
Cold Storage
Keeping Bitcoin completely offline — not connected to the internet. Hardware wallets and paper wallets are forms of cold storage. The safest way to store large amounts. (See Part 7.)
Confirmation
A Bitcoin transaction is “confirmed” when it’s been included in a block. More confirmations (more blocks built on top) mean more security. Most services consider 1 confirmation sufficient for small amounts and 6 for large amounts.
Consensus
The process by which all participants in the Bitcoin network agree on the state of the blockchain. Bitcoin uses Proof of Work to achieve consensus without a central authority. (See Part 3.)
Custodial Wallet
A wallet where someone else (like an exchange) holds your private keys. Convenient, but you don’t truly control your Bitcoin. “Not your keys, not your coins.” (See Part 7.)
D
Decentralization
A system where no single entity has control. Bitcoin is decentralized: no company, government, or person can shut it down or change its fundamental rules. Power is distributed across thousands of nodes worldwide.
DCA (Dollar-Cost Averaging)
Buying a fixed dollar amount of Bitcoin at regular intervals (e.g., $100 every week), regardless of price. This removes the stress of timing the market and smooths out volatility. The recommended strategy for beginners. (See Part 9.)
Difficulty Adjustment
Bitcoin automatically adjusts mining difficulty every 2,016 blocks (~2 weeks) to maintain a ~10-minute block time. If more miners join and blocks come faster, difficulty increases. If miners leave, difficulty decreases.
E
ETF (Exchange-Traded Fund)
A financial product that tracks Bitcoin’s price and trades on traditional stock exchanges. The landmark January 2024 approval of spot Bitcoin ETFs (like BlackRock’s IBIT and Fidelity’s FBTC) opened Bitcoin investment to mainstream investors. (See Part 5, 9.)
Exchange
A platform where you can buy, sell, and trade Bitcoin for fiat currency (USD, EUR, etc.) or other cryptocurrencies. Examples: Coinbase, Kraken, River. (See Part 6.)
F
Fiat Currency
Government-issued money (like USD, EUR, JPY) that isn’t backed by a physical commodity like gold. Its value comes from government decree (“fiat” = “let it be done” in Latin). Bitcoin is an alternative to fiat.
FOMO (Fear Of Missing Out)
The anxiety-driven impulse to buy Bitcoin when prices are rising rapidly (sometimes near the top). The opposite of DCA. A common beginner mistake. (See Part 9.)
Fork
A change to Bitcoin’s rules. A soft fork is backward-compatible (old nodes still work). A hard fork creates a split (new chain + old chain). Bitcoin Cash is a hard fork of Bitcoin from 2017.
FUD (Fear, Uncertainty, Doubt)
Misinformation or negative sentiment spread to create fear about Bitcoin. “Bitcoin is banned” (it’s not) or “Bitcoin was hacked” (it never was) are examples of FUD.
G
Genesis Block
The very first Bitcoin block, mined by Satoshi Nakamoto on January 3, 2009. It contained the embedded message: “The Times 03/Jan/2009 Chancellor on brink of second bailout for banks.” (See Part 5.)
H
Halving (The Halvening)
An event that occurs approximately every 4 years where the Bitcoin block reward is cut in half. This reduces the rate at which new Bitcoin is created. Previous halvings: 2012 (50→25), 2016 (25→12.5), 2020 (12.5→6.25), 2024 (6.25→3.125). (See Part 4.)
Hardware Wallet
A physical device (like Trezor, Ledger, Coldcard) that stores your private keys offline. Considered the most secure way to store Bitcoin for most people. (See Part 7.)
Hash Rate
A measure of the total computing power securing the Bitcoin network, expressed in hashes per second. Higher hash rate = more security. Bitcoin’s hash rate is the largest computing network in human history.
Hot Wallet
A wallet connected to the internet (mobile app, web wallet). More convenient but less secure than cold storage. Good for small, everyday amounts. (See Part 7.)
HODL
Originally a typo for “hold” in a 2013 forum post, now a meme/culture term for holding Bitcoin long-term regardless of price swings. Also retroactively interpreted as “Hold On for Dear Life.”
K
Keys (Public & Private)
The cryptographic foundation of Bitcoin ownership. Your private key is a secret code that proves ownership and allows you to spend Bitcoin — never share it. Your public key is derived from the private key and used to create addresses for receiving Bitcoin. (See Part 2.)
KYC (Know Your Customer)
Identity verification required by regulated exchanges and financial services. You provide ID, address, etc. to comply with anti-money laundering laws. P2P Bitcoin transactions and self-custody don’t require KYC.
L
Lightning Network
A Layer 2 protocol built on top of Bitcoin that enables instant, near-zero-fee transactions. It works by opening payment channels between participants, settling on-chain only when the channel closes. Ideal for small, frequent payments. (See Part 8.)
Liquidity
How easily Bitcoin can be bought or sold without significantly affecting its price. Bitcoin has deep liquidity on major exchanges.
M
Mining
The process of validating transactions and adding them to the blockchain. Miners use specialized computers to solve mathematical puzzles (Proof of Work). The winner earns newly created Bitcoin and transaction fees. (See Part 3.)
Mnemonic Phrase (Seed Phrase)
A sequence of 12 or 24 words that serves as a master backup for all private keys in your wallet. Losing your seed phrase = losing your Bitcoin. Write it on paper, never store it digitally, keep multiple copies in secure locations. (See Part 7.)
Multi-Signature (Multi-Sig)
A wallet that requires multiple private keys to authorize a transaction (e.g., 2-of-3: any 2 of 3 keys must sign). Adds security for shared funds or institutional custody. (See Part 7.)
N
Node
A computer running Bitcoin software that validates transactions and blocks, enforcing the network’s rules. Running a full node gives you the strongest security and privacy. ~50,000 Bitcoin nodes operate globally.
Non-Custodial Wallet
A wallet where YOU control the private keys. The opposite of a custodial wallet. “Your keys, your coins.” Recommended whenever possible. (See Part 7.)
P
P2P (Peer-to-Peer)
A network where participants interact directly without a central server. Bitcoin is P2P: you send value to another person without going through a bank or payment processor.
Paper Wallet
A piece of paper containing a Bitcoin private key and address, typically as QR codes. A simple form of cold storage. (See Part 7.)
Private Key
(See “Keys”)
Proof of Work (PoW)
The consensus mechanism Bitcoin uses. Miners must prove they’ve done computational work (solving a puzzle) to add a block. This makes it extremely expensive to attack the network — you’d need more computing power than half the entire network. (See Part 3.)
Public Key
(See “Keys”)
S
Satoshi (sat)
The smallest unit of Bitcoin: 0.00000001 BTC (one hundred-millionth). Named after Satoshi Nakamoto. Example: 1,000 sats = 0.00001 BTC. With Bitcoin’s rising price, people increasingly quote prices in sats.
Satoshi Nakamoto
The pseudonymous creator of Bitcoin. Published the white paper in 2008, launched the network in 2009, disappeared in 2011. Identity unknown. (See Part 1, Part 5.)
Seed Phrase
(See “Mnemonic Phrase”)
Self-Custody
Holding your own private keys rather than trusting a third party (like an exchange). The core Bitcoin principle: “Be your own bank.” (See Part 7.)
Spot Bitcoin ETF
An exchange-traded fund that directly holds Bitcoin (rather than futures contracts). The January 2024 SEC approval for 11 spot Bitcoin ETFs was a watershed moment for mainstream adoption. (See Part 5, 9.)
T
Transaction Fee
A small fee paid to miners to prioritize your transaction. Higher fees = faster confirmation. Fees vary with network congestion. Lightning Network transactions have near-zero fees.
Trustless
A system that doesn’t require you to trust any third party. Bitcoin is trustless: you verify transactions and balances yourself rather than trusting a bank. Code and mathematics replace trust.
U
UTXO (Unspent Transaction Output)
The technical term for “unspent Bitcoin.” Think of it like the change you get back after breaking a $20 bill. Your wallet balance is the sum of all your UTXOs. Understanding UTXOs helps with transaction privacy.
V
Volatility
The tendency of Bitcoin’s price to fluctuate significantly. Bitcoin is more volatile than traditional assets, which creates both opportunity and risk. Volatility has generally decreased over time as adoption grows. (See Part 9.)
W
Wallet
Software or hardware that manages your Bitcoin keys and allows you to send and receive. Wallets don’t “store” Bitcoin — Bitcoin exists on the blockchain. Wallets store the keys that control your Bitcoin. (See Part 6, 7.)
White Paper
The original Bitcoin document published by Satoshi Nakamoto on October 31, 2008: “Bitcoin: A Peer-to-Peer Electronic Cash System.” Nine pages that changed the world. (See Part 5.)
2
21 Million
The absolute maximum number of Bitcoin that will ever exist. Currently, ~20 million have been mined. The last Bitcoin will be mined around the year 2140. (See Part 4.)