Arbitrum is a suite of Ethereum scaling solutions that enables high-throughput, low cost smart contracts while remaining trustlessly secure. Arbitrum has three modes: AnyTrust Channels, AnyTrust Sidechains, and Arbitrum Rollup.
Arbitrum Rollup can scale any Ethereum contract. It's the ideal scaling solution for many DeFi apps and any application which is open to public participation. Arbitrum Rollup contracts enjoy the fully trustless security of the underlying blockchain, all while simultaneously increasing the dapp's capacity and greatly reducing costs.