Technology
How does a blockchain work?
A blockchain works as a shared digital ledger duplicated across many computers, where records are grouped into 'blocks' chained together cryptographically. Because everyone holds a copy and each block locks in the previous one, the record is extremely hard to tamper with.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how a blockchain works.
Step by step
- 1Transactions are grouped into blocks and added in order.
- 2Each block is cryptographically linked to the one before it.
- 3Copies of the ledger are stored across many computers (decentralized).
- 4Changing an old record would break the chain and be rejected.
- 5It enables trust without a central authority.
Frequently asked questions
- What makes a blockchain secure?
- Each block is cryptographically tied to the previous one and copied across many computers, so altering a record breaks the chain and is rejected by the network.
- Why is a blockchain called 'decentralized'?
- No single party holds the master copy — the ledger is duplicated across many independent computers that must agree on it.
- What is a blockchain used for?
- Cryptocurrencies, but also supply-chain tracking, digital contracts, and records where tamper resistance and shared trust matter.