What is the concept of a mining pool? The miners together start to check as many block hashes as possible on behalf of the mining pool.
What is the reward? The block reward is distributed among the pool’s participants based on the share of hashing power they own in the pool.
How does it work? At first, the miners connect to the same network. Then the system distributes different ranges of the possible values to check between the miners, the pool mines bitcoins or whatever cryptocurrency together, and eventually distributes the profit among the participants.