Mempool

The 'memory pool' of transactions that have been broadcast to a blockchain but not yet included in a block. Every node maintains its own view of the mempool; public mempool transactions are visible to anyone running a node, which is the foundation of MEV (front-running, sandwich attacks). Private mempools (Flashbots Protect, MEV-Share) submit transactions directly to block builders to avoid public-mempool visibility. The mempool is also the inspection point for fee estimation and pending-transaction monitoring.