The mempool is often characterized as a dark forest — a mysterious place full of unexpected events and adversaries. After submitting a transaction you wait, and (hopefully) it gets confirmed. Or it fails. Or it gets stuck. Or it just disappears. Why? Because your pending transaction is invisibly competing with tens of thousands of other pending transactions for limited block space.

The stakes – and the risks – include the time to settle, transaction fees, the terms of settlement, and more.

You have next-to-zero visibility into this critical competition because it plays out in real-time and at a global scale, inside the thousands of unique nodes that comprise Ethereum's network. This lack of transparency surrounding in-flight transactions creates exploitable opportunities for well-informed, well-resourced, and very real adversarial actors.

And since any single node contains only a partial view of the global mempool, it is difficult and expensive to manage the mempool on your own.