A blockchain is a distributed digital ledger that records transactions across a network of computers. Each block contains multiple transactions and is cryptographically linked to the previous block, forming a chain.
Key properties of blockchain include: Decentralization with no single point of control, Immutability where records cannot be altered, Transparency with publicly verifiable transactions, Security through cryptographic hashing, and Consensus mechanisms for network agreement.
Types of blockchains include Public blockchains (Bitcoin, Ethereum) that anyone can join, Private blockchains controlled by organizations, and Hybrid blockchains combining elements of both.
Blockchain technology has applications beyond cryptocurrency, including supply chain management, healthcare records, voting systems, digital identity, and smart contracts.