Before diving into QRL's quantum-resistant cryptography, it helps to be clear on what a blockchain actually is. Strip away the hype and it's a surprisingly simple idea.
A shared ledger with no owner
A ledger is just a record of transactions — who paid whom, and when. A normal ledger lives with one trusted party: your bank keeps the record of your account.
A blockchain is a ledger that is copied across thousands of independent computers, with no single owner. They all hold the same history and follow the same rules to keep it in sync. There is no central operator to trust — or to hack, censor, or shut down.
The hard problem this creates is agreement: how do thousands of strangers settle on one shared history? The answer is the consensus mechanism, which we cover separately.
Why "block" and why "chain"
Transactions aren't written one at a time. They're collected into blocks — batches confirmed together at a regular rhythm. Each block carries a hash (a cryptographic fingerprint) of the block before it.
[ Block 100 ] → [ Block 101 ] → [ Block 102 ] → …
hash of 99 hash of 100 hash of 101
That backward link is the "chain." It's also the source of the blockchain's tamper-resistance: change anything in an old block and its hash changes, which breaks the link in every block that follows. To get away with it you'd have to re-make all those blocks faster than the rest of the network makes new ones — which the consensus rules are designed to make absurdly expensive.
What lives on a blockchain
At minimum, a blockchain records balances and transfers of its native coin. Many chains also run programs — smart contracts — that move value under coded rules. This is one place QRL's two chains differ: QRL 2.0 supports smart contracts, while QRL Legacy supports only a fixed set of transaction types.
Crucially, the ledger is append-only and public. Anyone can read it, and once something is confirmed and buried under enough later blocks, it is effectively permanent. That's exactly what a block explorer like this one lets you browse.
Where QRL fits
QRL is a blockchain with one distinguishing feature: the signatures that authorise its transactions are quantum-resistant, unlike the ECDSA most chains use. Everything else on this page — blocks, chaining, a shared ledger, consensus — still applies. QRL just swaps the cryptography that protects your funds for schemes a quantum computer can't break.
Where to go next
- Blocks and transactions — what's actually inside a block.
- Wallets, addresses and keys — how ownership works.
- Proof-of-Work vs Proof-of-Stake — how blocks get agreed on.