A miner is a person or specialized hardware that mines bitcoin and other cryptocurrencies using PoW. Miners confirm transactions, which keeps the payment system running and maintains the consensus of a unified and unchanging state of the entire network. They receive bitcoins or other relevant cryptocurrency as a reward.
During the mining process, miners perform complex calculations, and whoever is the first to find a solution that meets the necessary criteria gets the right to form the block. During the formation of a new block, the miner is rewarded with a certain amount of cryptocurrency. Many miners are “competing” for this reward at the same time. Transactions that are included in a block are considered confirmed only after a certain number of blocks in a row (six for bitcoin) are calculated.