Each “block” of records is cryptographically linked to the one before it, forming a chain that is extremely hard to alter after the fact. Because copies of the ledger are held by many independent participants, no single party can quietly rewrite history.
Blockchains are the technology underpinning Bitcoin, Ethereum and most cryptocurrencies. Different blockchains make different trade-offs between decentralisation, speed and cost.
Key takeaways
- A blockchain is a shared digital ledger that records transactions in linked blocks maintained across many computers.
- Once data is confirmed and added, altering past records is extremely difficult, which is why blockchains are called tamper-resistant.
- No single party controls a public blockchain; the network validates entries by consensus rather than trusting one authority.
Blockchain — frequently asked questions
Is a blockchain the same as a cryptocurrency?
No. A blockchain is the underlying ledger technology, while a cryptocurrency is one type of asset that can be recorded on it.
Are blockchains completely anonymous?
Usually not. Most public blockchains are pseudonymous, meaning activity is tied to addresses that can sometimes be linked to real identities.
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