Blockchain

In a blockchain, transactions are grouped into blocks. Each new block contains a unique code, called a hash, linking it to the previous block, creating a chain. Changing any past record would require altering every block that came after it on most of the network's computers at once, which is practically impossible on large networks.

Instead of relying on a central authority, such as a bank, to maintain records, a blockchain is maintained by a network of participants who agree on which transactions are valid using rules called consensus mechanisms.

Blockchain is the technology behind cryptocurrencies such as Bitcoin. But it has potential uses beyond digital currencies. For example, a company might use a blockchain to track goods through a supply chain, giving all parties a shared, trustworthy record of where a product came from and how it travelled.

Other proposed uses include settling securities trades, recording property titles, issuing digital identity and creating smart contracts that execute automatically when conditions are met. Many projects remain experimental, and critics note that a traditional database is often simpler and cheaper when participants already trust a central organisation.