Blockchain

A blockchain is a decentralized, distributed database in which every participant holds an identical copy of all recorded data. Unlike traditional databases controlled by a single institution, no single entity governs a blockchain: each participant can add new records, but past data cannot be altered. This combination of openness and immutability makes it the foundation of most cryptocurrencies and a growing range of other applications. Transactions are grouped into blocks, each cryptographically linked to the previous one, forming an unbroken chain that is tamper-evident by design.

Blockchains rely on consensus protocols to agree on the state of the ledger without a central authority. The two dominant approaches are Proof of Work, used by Bitcoin, where miners compete to solve a mathematical puzzle, and Proof of Stake, now used by Ethereum and many other networks, where validators lock up coins as collateral to earn the right to confirm transactions. Beyond cryptocurrency, blockchain enables smart contracts: self-executing agreements recorded on-chain that automate everything from mortgage processing to supply-chain tracking. For a deeper breakdown, see our full guide on blockchain.