Most explanations of Bitcoin mining tell you that miners “solve complex mathematical puzzles”, then stop. The sentence is true and almost useless. It says nothing about what the puzzle is, why it exists, or why solving it is worth billions in electricity every year. A better route is to follow a single payment, then ask what all that energy actually buys.
The problem mining solves
Bitcoin has no bank and no central authority. So who decides which transactions are valid, and in what order? Without an agreed order, the same coin could be spent twice and the system would collapse into argument. Bitcoin’s answer is to let anyone compete for the right to write the next page of the ledger, and to make winning that right expensive. The expense is the point.
From your payment to a block
When you send bitcoin, the payment is first broadcast to thousands of independent computers, called nodes, which check that the coins exist, that they are yours, and that they have not already been spent. It then waits in a global queue, the mempool, alongside every other pending transaction. Miners empty that queue: roughly every ten minutes, they gather waiting payments into a bundle called a block and compete to have it accepted as the ledger’s next page.
The puzzle is a guessing game
Every block must carry a digital fingerprint, produced by running its data through a one-way function called a hash. Change the input by one character and the output changes completely and unpredictably. The network’s rule is that a block is only valid if its fingerprint begins with a certain number of zeros, and the only way to find one is to keep adjusting a small number inside the block, the nonce, and hash again. Guess, check, guess, check, billions of times per second. Mining is not clever mathematics; it is a lottery in which more electricity buys more tickets. Today, the network makes close to a zettahash of guesses every second, a one followed by 21 zeros.1
Why it always takes ten minutes
Machines keep improving, yet blocks still arrive roughly every ten minutes. Individual blocks are a lottery, arriving in anything from seconds to the better part of an hour; ten minutes is only the average. What keeps that average steady while machines keep improving is the difficulty reset every 2,016 blocks: found too fast and the bar rises, too slow and it falls. A self-correcting clock, with no committee and no manager, because the network resets the required difficulty every two weeks. More competition raises the bar; less competition lowers it.
The reward
The winning miner collects newly created bitcoin, currently 3.125 BTC per block and halving roughly every four years, plus the fees attached to the payments it includes.2 This reward is the only way new bitcoin enters circulation, and it adds up to a real business: across the network, mining currently generates roughly $29M in revenue per day.3
The energy is the security
So is the electricity wasted on a guessing game? The honest answer is that the cost is doing a job. To rewrite Bitcoin’s history, an attacker would have to redo all of that guessing faster than the rest of the network combined, and the bill makes the attack economically self-defeating. The energy is not a side effect of the security; it is the security. Mining converts electricity into trust, so that no single party needs to be trusted at all.
What this leaves open is the following question: who owns all these machines? The answer is an industrial sector, with listed companies, power contracts and quarterly earnings, that increasingly looks like critical infrastructure.
Sources
1 Hashrate Index / CoinWarz network data, July 2026: Bitcoin network hashrate near 960 EH/s, having first crossed 1 ZH/s in December 2025. Refresh at publication.
2 Bitcoin protocol: block subsidy of 3.125 BTC since the April 2024 halving.
3 Token Terminal, 12 July 2026: total daily miner revenue of approximately $28.9M (block subsidy plus transaction fees).