The mempool is the waiting room: transactions broadcast to the network but not yet in a block, visible to everyone, ordered by fee when a validator builds. It is where your payment sits between signing and settling, and its depth is why fees spike at rush hour.
For payments the mempool explains the wait: a transaction that pays the prevailing fee rides the next block; one that skimps waits until traffic clears or gets replaced. Checkouts quote the current fee precisely so the wait matches expectations.
U.CASH quotes network fees with the transaction and watches the chain against your confirmation policy, so mempool delays surface as status, not surprises.
Every term behind the rails, the assets, and the settlement.