Gas is the price of changing a blockchain's state: every transfer, swap, and mint bids for block space, and the fee (paid in the chain's native token, ETH or SOL or TRX) compensates the network for including the change. Fees float with demand; congestion raises them, quiet chains lower them.
For payments, gas is the fine print. A rail that costs cents works for coffee; a rail that costs dollars at peak does not. Modern L2s and Solana keep fees low enough that per-transaction settlement is viable again.
U.CASH quotes the network fee with every transaction before signature, per chain, and the swap's flat platform fee sits beside it, visible, with no spread hidden in the route.
Every term behind the rails, the assets, and the settlement.