Notitia
A shared, tamper-proof, public ledger.
A blockchain is a digital ledger shared across thousands of computers. Transactions are grouped into “blocks”, cryptographically chained together - hence the name.
Once written, data cannot be changed without rewriting the whole chain on a majority of the network - which is what makes a blockchain tamper-proof.
You receive a bitcoin payment. An attacker with 10% of the hash power tries to rewrite history.
Each added block makes a rewrite exponentially less likely. A pro scales confirmations to the amount: one for a coffee, six or more for a large settlement.
Test your understanding with a quick interactive quiz.