The technology, plainly.
WHAT IT IS
A record of transactions, replicated across many computers, where participants agree on its contents without a central authority.
WHAT A BLOCK IS
A batch of transactions, with a reference to the previous block.
WHAT CHAINS THEM
Each block containing a cryptographic fingerprint of the one before.
WHY THAT MATTERS
Changing an old block changes its fingerprint, which breaks every block after it.
WHAT THAT PROVIDES
Tamper evidence: alteration is detectable, not impossible.
WHAT MAKES ALTERATION IMPRACTICAL
The cost of redoing the work for every subsequent block, faster than the network extends it.
WHAT THE NETWORK IS
Independent computers, each holding a copy and validating transactions against the rules.
WHAT CONSENSUS MEANS
Agreement on which version of the record is correct.
WHAT THE TECHNOLOGY GENUINELY PROVIDES
A record no single party controls Verifiable history Execution of rules without a trusted intermediary Resistance to censorship, in open networks
WHAT IT DOES NOT PROVIDE
Truth about anything outside itself Reversibility of mistakes Privacy, by default Performance comparable to ordinary databases
WHAT TO ASK OF ANY PROPOSED USE
Does this require the absence of a trusted party?
