Mempool

The mempool (“memory pool”) is the waiting area where valid, unconfirmed transactions sit after being broadcast, before a miner or validator includes them in a block. Each node keeps its own view of pending transactions, so mempools can differ slightly across the network. When demand is high, the mempool grows and transactions offering higher fees are typically picked first.

A common misconception is that a broadcast transaction is already final; until it is included in a block and confirmed, it remains pending and can still be dropped or replaced.