Glossary
Miner
A node that produces blocks on a proof-of-work blockchain by spending energy to find a hash below the network's difficulty target.
On a proof-of-work chain, miners compete to find a nonce that makes their candidate block's hash fall below a target. The first miner to succeed broadcasts the block, claims the block reward and fees, and the race resets.
Mining concentrates around the cheapest electricity and the best ASICs. The economic intuition is simple: rewriting history would require out-mining the rest of the network, and at current hashrates that is prohibitively expensive.