Blockchain is a decentralized digital ledger that records transactions across a network of computers. It is maintained by a network of users and computers, instead of a single central authority, and uses cryptography to secure the transactions and prevent tampering or revision of the data.
In a blockchain, transactions are grouped together into blocks and added to the existing chain of blocks in a linear, chronological order. Each block contains a unique cryptographic hash of the previous block, forming a secure and unalterable chain of records. This makes the blockchain highly secure and resistant to tampering, since any attempt to change the data in a block would result in a change to the hash, which would be easily detected by the network.
Blockchains have the potential to revolutionize a wide range of industries by enabling secure, transparent and tamper-proof record-keeping and transactions. The most well-known application of blockchain technology is the cryptocurrency Bitcoin, but blockchains are also being used in a variety of other fields, including finance, supply chain management, digital identity and voting systems.