The Bitcoin Mempool is the Bitcoin network’s waiting room for all unconfirmed transactions before they are consolidated into blocks. On the Bitcoin network, transactions are not directly added to the blockchain in the form of a block. They are initially collected and then ‘processed’ in the Bitcoin mempool. The mempool is accessible to every Full Node on the network, that is any node that stores the entire history of Bitcoin transactions.
The miners‘ role is to validate these unvalidated mempool transactions and integrate them into the Bitcoin blockchain after they are validated. Miners cluster memepool transactions together in ‘blocks’ and then compete with one another in a race to solve a complex mathematical puzzle. The first miner to solve the puzzle correctly has the privilege of adding the block to the blockchain and claiming the reward attached to it.