What Is the ‘Mempool’ in the Context of Cryptocurrency Mining?

The mempool, short for memory pool, is a waiting area for all valid, unconfirmed transactions that have been broadcast to the network. Each node maintains its own version of the mempool.

Miners select transactions from their mempool to include in the block they are currently trying to mine. Transactions wait in the mempool until a miner includes them or they expire after a set time.