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. The following documentation describes how to use Arbitrum Rollup, which is currently live on testnet. Whether you're a developer that just wants to start building or you're curious into digging deeper into the internals of Arbitrum and how it works, this site is the right place for you.