BTC / protocol guide

Proof of work and the UTXO ledger

Bitcoin combines proof of work, a UTXO ledger and difficulty adjustment to order transactions without a central operator.

Source-backed essentials

Blocks commit to ordered transactions and extend the chain with the most accumulated proof of work.
Difficulty adjusts periodically to keep block production near the protocol target over time.
Wallets control keys; they do not store coins outside the public ledger.