Arbitrum is a technology suite designed to scale Ethereum. You can use Arbitrum chains to do all things you do on Ethereum — use Web3 apps, deploy smart contracts, etc., but your transactions will be cheaper and faster. Our flagship product — Arbitrum Rollup — is an Optimistic rollup protocol that inherits Ethereum-level security.
Nitro represents the latest step in the evolution of Arbitrum technology; it is an upgrade from the tech stack first released on the mainnet Arbitrum One chain, which we now refer to as “Arbitrum Classic”.