What do Bitcoin miners actually do?
When someone sends bitcoin, their transaction is broadcast to the network. Miners select valid transactions and group them into a candidate new block.
But making a block is not enough. To add it to Bitcoin’s shared history, a miner must find valid Proof of Work.
How does Proof of Work work?
Imagine a competition in which people keep trying different numbers until one produces a result meeting a particular rule. There is no simple shortcut for predicting the winning result.
Bitcoin miners repeatedly calculate the hash of a candidate block header, changing parts of it, searching for a result below the network’s difficulty target.
Once a valid result is found, the block can be broadcast. Other nodes can quickly check the result and the remaining consensus rules. Finding the solution is difficult; checking it is relatively easy.
How does mining help secure Bitcoin?
Proof of Work makes replacing the accepted transaction history costly. Anyone trying to change an older block would need to redo the relevant work and compete against the chain the rest of the network continues building.
As additional blocks arrive, the work needed to replace that history generally increases. This is one reason transaction confirmations matter.
For how blocks link together and get verified by the network, read the article about the blockchain.
How are miners rewarded?
A miner who produces a valid block can claim two kinds of reward: the block subsidy, which creates newly issued bitcoin under the protocol’s rules, and the transaction fees from included transactions.
Since the 2024 halving, the block subsidy has been 3.125 BTC per block until the next halving. Many miners work together in mining pools and share payouts under the pool’s rules. Not every individual miner receives 3.125 BTC.
To understand how new bitcoin issuance slows down, read why there are only 21 million bitcoin.
Why does Bitcoin mining use electricity?
Repeated calculations require machines and electricity. Competitive Bitcoin mining today mainly uses specialized equipment called ASIC miners.
This real-world cost is part of Proof of Work. It also raises important questions about energy sources, environmental impact, and the sustainability of mining.
What is the difference between miners and nodes?
Miners compete to propose new blocks. Full nodes independently verify whether the blocks and transactions follow the consensus rules they enforce.
A miner cannot force a full node to accept an invalid block, even after spending a great deal of computing power. Simply put: miners propose blocks; nodes verify them.
Why does Bitcoin target about 10 minutes per block?
Bitcoin adjusts mining difficulty every 2,016 blocks to keep the average time between blocks near 10 minutes.
This is not an exact timer. Some blocks arrive within seconds, while others take much longer.