Mempool
The pool of unconfirmed transactions waiting to be included in a block.
The mempool (memory pool) is a temporary holding area where broadcast transactions wait for a validator or miner to pick them up and include them in a block. Every node maintains its own version of the mempool.
Validators select transactions from the mempool — typically prioritising those with the highest fees. During periods of congestion, the mempool can swell to hundreds of thousands of transactions and fees spike accordingly.
The public visibility of the mempool enables MEV (Maximal Extractable Value) strategies, where bots monitor pending transactions and insert their own to profit from arbitrage or liquidations before the original transaction executes.