Mempool

A mempool, short for memory pool, is a temporary storage area used by each node in a blockchain network to hold transactions that haven’t yet been added to a block. When you send a transaction, it enters the mempool and waits there until a miner includes it in a new block, at which point it’s confirmed and removed from the pool. Each node maintains its own mempool—there isn’t a universal, shared pool—so some differences can exist between nodes. Transactions in the mempool are relayed across the network, helping keep nodes up to date. Miners select transactions from their local mempools to assemble the next block, often choosing those with the highest fees first.