What is a Blockchain?

A blockchain is a decentralized digital ledger that records transactions across multiple computers in such a way that the records cannot be altered retroactively without altering all subsequent blocks. Each block contains a list of transactions, a timestamp, and a cryptographic hash of the previous block, forming a chain of blocks. This decentralized nature makes blockchains secure and resistant to tampering, censorship, or central authority control. Blockchain technology powers cryptocurrencies, smart contracts, decentralized applications (dApps), and provides the foundation for various industries, including finance, supply chain, and healthcare.