Any cryptocurrency other than Bitcoin. The term combines "alternative" and "coin". Examples include Ethereum (ETH), Solana (SOL), and Litecoin (LTC).

A unique alphanumeric string that represents a destination for a Bitcoin transaction — similar to a bank account number. Addresses are derived from public keys and typically begin with "1", "3", or "bc1".

The world's first and largest decentralised cryptocurrency, created in 2009 by Satoshi Nakamoto. Bitcoin operates on a peer-to-peer network with a fixed supply of 21 million coins.

A distributed, immutable public ledger that records all cryptocurrency transactions in chronological order. Each "block" contains a batch of transactions and is cryptographically linked to the previous block, forming a "chain".

A payment method that allows consumers to purchase goods or services immediately and pay in instalments over time. Bitcoin BNPL applies this concept using cryptocurrency as the payment medium.

The amount of Bitcoin awarded to a miner for successfully adding a new block to the blockchain. The reward started at 50 BTC in 2009 and halves approximately every four years.

A cryptocurrency wallet that is not connected to the internet, such as a hardware device (e.g. Ledger, Trezor) or a paper wallet. Cold wallets are considered the most secure way to store large amounts of cryptocurrency.

A digital or virtual currency that uses cryptography for security and operates on a decentralised network, typically a blockchain. Bitcoin is the first and most well-known cryptocurrency.

The science of securing information using mathematical algorithms. Bitcoin uses public-key cryptography to create digital signatures that prove ownership of funds without revealing private keys.

Financial services and products built on blockchain networks that operate without traditional intermediaries such as banks. DeFi includes lending, borrowing, trading, and earning interest using smart contracts.

Any asset that exists in digital form and has value, including cryptocurrencies, non-fungible tokens (NFTs), and tokenised real-world assets.

A platform where users can buy, sell, and trade cryptocurrencies. Centralised exchanges (CEX) are operated by companies; decentralised exchanges (DEX) operate via smart contracts without a central authority.

Government-issued currency not backed by a physical commodity such as gold. Examples include GBP (British Pound), USD (US Dollar), and EUR (Euro). Bitcoin is often described as an alternative to fiat currency.

A change to the Bitcoin protocol. A soft fork is backward-compatible; a hard fork creates a permanent divergence, potentially resulting in a new cryptocurrency (e.g. Bitcoin Cash was created via a hard fork of Bitcoin in 2017).

A fee paid to compensate for the computing energy required to process and validate transactions on the Ethereum network. Not applicable to Bitcoin, which uses transaction fees instead.

An event that occurs approximately every four years (every 210,000 blocks) where the Bitcoin block reward is cut in half. Halvings reduce the rate of new Bitcoin supply, historically preceding significant price increases.

The total computational power being used by the Bitcoin network to process transactions and mine new blocks. A higher hash rate means a more secure network.

A cryptocurrency wallet connected to the internet, such as a mobile app or exchange account. Hot wallets are convenient for frequent transactions but are more vulnerable to hacking than cold wallets.

A regulatory requirement for financial services companies to verify the identity of their customers. Regulated cryptocurrency exchanges require KYC before users can buy or sell crypto.

A second-layer payment protocol built on top of Bitcoin that enables near-instant, near-zero-fee transactions by opening off-chain payment channels between parties.

The total value of a cryptocurrency, calculated by multiplying the current price by the total circulating supply. Bitcoin's market cap is the largest of any cryptocurrency.

The process of verifying Bitcoin transactions and adding them to the blockchain. Miners use specialised computers to solve complex mathematical puzzles and are rewarded with newly created Bitcoin.

A unique digital asset recorded on a blockchain that represents ownership of a specific item — such as digital art, music, or collectibles. Unlike Bitcoin, each NFT is unique and cannot be exchanged on a like-for-like basis.

A computer that participates in the Bitcoin network by storing a copy of the blockchain and relaying transactions. Full nodes enforce the rules of the Bitcoin protocol.

A secret cryptographic key that proves ownership of Bitcoin and is used to sign transactions. Anyone with access to your private key can spend your Bitcoin — it must be kept completely secure.

A cryptographic key derived from a private key that can be shared publicly. Bitcoin addresses are derived from public keys. Sharing your public key or address does not compromise your funds.

The consensus mechanism used by Bitcoin where miners compete to solve complex mathematical puzzles to validate transactions and create new blocks. It requires significant computational energy, making the network secure.

The smallest unit of Bitcoin, equal to 0.00000001 BTC (one hundred millionth of a Bitcoin). Named after Bitcoin's creator, Satoshi Nakamoto. As Bitcoin's price rises, transactions are increasingly denominated in satoshis.

A sequence of 12–24 randomly generated words that serves as a master backup for a cryptocurrency wallet. Anyone with your seed phrase can access and spend all funds in your wallet — store it securely offline.

Self-executing code stored on a blockchain that automatically enforces the terms of an agreement when predefined conditions are met. Smart contracts are the foundation of DeFi and NFT platforms.

A cryptocurrency designed to maintain a stable value, typically pegged to a fiat currency like the US Dollar. Examples include USDC, USDT (Tether), and DAI. Stablecoins combine blockchain benefits with price stability.

A small amount of Bitcoin paid to miners to prioritise and process a transaction. Higher fees result in faster confirmation times, especially during periods of high network congestion.

Software or hardware that stores the private keys needed to access and spend cryptocurrency. Wallets do not store coins directly — they store the keys that prove ownership of coins on the blockchain.

A technical document that describes the design, purpose, and mechanics of a cryptocurrency or blockchain project. Bitcoin's whitepaper, published by Satoshi Nakamoto in 2008, is titled "Bitcoin: A Peer-to-Peer Electronic Cash System".