A Bitcoin mining pool is a collaborative effort by miners to pool their resources together and share their hashing power while splitting the reward equally according to the amount of work they contributed to the probability of finding a block.
A “share” is awarded to members of the mining pool who present a valid partial proof-of-work. Mining in a pool is a way to increase the chances of finding a block, thus receiving a reward.
The reward is split among all participants in the pool according to the amount of work they contributed to the probability of finding a block. This means that each miner will receive a portion of the total reward based on the amount of work they put in.
The pooling of resources ensures that even small miners can receive a reward proportional to their contributed mining power, instead of only large miners receiving rewards.
The collective power of all miners in the pool is used to solve a block and the reward is then split among all participants. This means that the more people join a mining pool, the more resources are available and the higher the chances of finding a block and receiving a reward.