Technology
What is Blockchain?
A blockchain is a shared digital ledger that records transactions across many computers so the record can't be changed retroactively. Each 'block' of data is cryptographically linked to the one before it, forming a tamper-evident chain.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains blockchain.
Key things to understand
- 1It's decentralized: copies live on many computers (nodes), so there's no single point of control or failure.
- 2Each block contains data, a timestamp, and a cryptographic fingerprint (hash) of the previous block.
- 3Changing one block would break every block after it, which is what makes tampering obvious.
- 4It underpins cryptocurrencies like Bitcoin, but also supply-chain tracking, digital identity, and smart contracts.
Frequently asked questions
- Is blockchain the same as Bitcoin?
- No. Bitcoin is one application of blockchain. The blockchain is the underlying technology that many other systems also use.
- Why is blockchain considered secure?
- Because records are distributed across many nodes and cryptographically chained, altering history would require controlling most of the network simultaneously.
- What is a smart contract?
- Code stored on a blockchain that runs automatically when conditions are met — for example, releasing a payment once a delivery is confirmed.