A Layer 2 is a network that settles to another chain (the Layer 1) while executing transactions on its own, cheaper, faster ledger: Arbitrum and the Orbit chains, Base, Polygon, and their peers.
The bargain: L2 fees are cents where L1 fees are dollars, with security ultimately anchored to the base chain. For payments the L2s are where the volume lives; for large single transfers the L1's stronger assumptions sometimes still win.
A Layer 2 is a network that executes transactions on its own ledger while settling security to a base chain. The L2 batches or sequences activity, then posts commitments to the L1, whose validators enforce the final word. Users get mainnet-grade assurances at the L2's cost and speed: blocks in hundreds of milliseconds, fees in cents.
Families differ in how they prove correctness. Optimistic rollups post results and allow a challenge window in which fraud proofs can revert invalid batches. Zero-knowledge rollups post validity proofs that verification itself certifies. Both anchor to the L1; the difference is who has to watch and how quickly the result becomes as hard as the base chain's.
For payments the summary is simpler: L2s are where the economics work. A rail that costs cents and settles in under a second serves commerce; one that costs dollars and minutes serves settlement batches. That arithmetic, not ideology, is why checkout volume concentrates on L2s and Solana.
Base, an OP Stack L2, settles typical token transfers in about two seconds with ETH-denominated gas of a cent or less, while anchoring to Ethereum. Robinhood Chain, an Arbitrum Orbit L2, runs about 250 millisecond blocks for its tokenized assets.
Most of U.CASH's supported networks are L2s (Base, Arbitrum, Polygon, and the Robinhood Chain among them) which is why typical settlement fees run to cents.
Merchants benefit directly: more of each receipt survives the rail, and confirmation arrives fast enough for retail. U.CASH's network roster is weighted toward L2s precisely because payment economics demand it. A note on choosing among them for a settlement asset: the practical differences are gas token, block time, and form availability of the assets you actually settle in. Robinhood Chain carries its tokenized roster at about 250 millisecond blocks, Base runs broad crypto liquidity at about two second blocks, and the right choice is whichever holds your corridor's tokens natively.
Every term behind the rails, the assets, and the settlement.