A blockchain is a digital ledger or database that is distributed across a network of computers or nodes. It is used to store a record of transactions, which are verified and validated by the network of nodes. Each block in the chain contains a timestamp and a link to the previous block, creating a secure and tamper-proof chain of data.
Blockchains were first introduced in 2008 as part of the Bitcoin cryptocurrency, but have since been adopted for use in a variety of industries and applications beyond cryptocurrency. The key feature of a blockchain is its decentralized nature, which means that no single entity or organization has control over the network. Instead, the network is maintained and secured by a large number of independent nodes that work together to validate and record transactions.
Blockchains use complex algorithms and cryptography to ensure the security and integrity of the data stored on the network. Transactions are verified by nodes using a consensus mechanism, which is typically a form of proof-of-work or proof-of-stake. Once a transaction is verified, it is added to the blockchain and cannot be altered or deleted.
Because of their decentralized and secure nature, blockchains have the potential to revolutionize a wide range of industries, from finance and banking to supply chain management and voting systems.