Beginner
What is a blockchain?
The shared ledger behind every cryptocurrency, explained without jargon.
5 min read
A ledger many people keep
A blockchain is a record of transactions that many independent computers keep in sync. Instead of one company maintaining the books, the network agrees on each new page — a block — and links it to the previous one.
Because each block references the one before it, changing an old entry would mean rewriting everything after it, which the rest of the network would reject.
How agreement is reached
Networks use a consensus mechanism to decide which block comes next.
- Proof of Work: computers compete to solve a puzzle; the winner proposes the block (Bitcoin).
- Proof of Stake: validators lock up tokens as collateral and are selected to propose blocks (Ethereum).
Why it matters
Blockchains let strangers transact without a central intermediary, and make the history of an asset publicly verifiable.