Blockchain
A public record where each new page is locked to the one before it.
In plain words
A blockchain is a shared record book, built one block at a time. Each block carries a fingerprint of the block before it. Change anything old and every later fingerprint breaks — everyone would notice. Bitcoin's record is public: anyone can download it, check it, and add to it by mining. Nobody controls it, and nobody can quietly rewrite it.
Why it matters
- Lets strangers agree on one history without trusting each other.
- Makes tampering obvious: change one block and everything after it breaks.
- Bitcoin's has run since 2009, and every payment ever made is still checkable.
Numbers that matter
- ~10 minutes — a new block is added, on average.
- 2009 — every payment since then is on the chain.
Not to be confused with
- "Blockchain technology" — corporate chains copy the shape but drop the openness that makes Bitcoin's work.
- Bitcoin — the money. The blockchain is its record book.
Go deeper
Updated 2026-07-29