How it works
Miners compete to find a number that, when combined with the next block header and hashed, produces a result below the network’s difficulty target. The first to find such a number broadcasts the block. Other nodes verify the solution instantly. The successful miner receives the block reward plus all transaction fees. The network adjusts difficulty every 2,016 blocks (about every two weeks for Bitcoin) so block time stays at roughly 10 minutes.
Example
Bitcoin’s network currently processes about 600 quintillion hashes per second collectively. A single high-end ASIC at 100 terahash per second contributes roughly 1 part in 6 million of the total. The energy cost of attacking the network (51 percent of hash rate) requires acquiring hardware and electricity worth tens of billions of dollars. That cost is the security guarantee.
Why it matters
Proof of work made Bitcoin and the broader crypto industry possible. Its security model is the most battle-tested in the space: Bitcoin has run continuously since January 2009 without a successful 51 percent attack. The trade-offs are energy consumption (estimated 0.5 percent of global electricity for Bitcoin alone) and hardware-driven centralisation pressure as ASIC manufacturing concentrates. Proof of stake networks made a different choice on these trade-offs.
