A distributed digital ledger recording transactions across multiple computers.
A blockchain is a distributed ledger technology recording transactions in blocks linked chronologically. Each block contains transaction data and a reference to the previous block, creating an immutable chain. Blockchains are decentralized (no single authority controls them) and transparent (all transactions are visible). Bitcoin and Ethereum use blockchain technology. Benefits include transparency, security, and decentralization; drawbacks include scalability challenges and energy consumption. Blockchain has applications beyond cryptocurrency: supply chain tracking, smart contracts, and record-keeping. Understanding blockchain is increasingly important for evaluating cryptocurrency and fintech investments.