Proof of Work (PoW)
Consensus where miners solve cryptographic puzzles to add blocks.
PoW (Bitcoin's original): miners (ASICs) solve crypto puzzles. Winner adds block + reward. Difficulty adjusts every 2016 blocks. Pros: most secure, physically grounded. Cons: energy-heavy (BTC ~150 TWh/year = Argentina).
In plain words
Bitcoin's security model: thousands of computers worldwide solve the same math puzzle, the first to solve it adds the block and gets the BTC reward. Requires huge energy, but that energy is exactly what gives BTC the strongest security in the world. Breaking it would cost billions.
Example
BTC PoW: 700 EH/s hash, ~150 TWh/year, 51% attack ~$30B. LTC PoW Scrypt: 1 PH/s. ETH used PoW until Sep 2022, switched to PoS (-99.95% energy).
Also known as: PoW, proof of work, mining