A Bitcoin mining pool miner is a person or group of people who are part of a larger pool of miners and who contribute their computing power to the mining of Bitcoin transactions. This is done in order to increase the chances of successfully finding the solution to the mathematical problem that is required to process and confirm Bitcoin transactions, known as ‘mining’.

The miners are rewarded with newly created Bitcoin, as well as transaction fees, for providing their computing power to the network. When miners join a mining pool, they become part of a larger group of miners who are all working towards the same goal of finding the solution to the mathematical problem. In a pool, each miner is assigned a ‘share’ of the work, which is proportional to the amount of computing power that they have contributed.

The rewards for successfully finding the solution to the problem are then split among the miners in the pool, based on the contribution that each miner has made. This means that the miners in the pool are able to share in the rewards for finding the solution, even if only one of the miners in the pool actually finds the solution.

By joining a mining pool, individual miners are able to increase their chances of finding a solution to the mathematical problem and earning rewards. This is because the combined computing power of the pool is much greater than that of any single miner, and thus the chances of finding the solution are much higher.