Arbitrum is a protocol that makes Ethereum transactions faster and cheaper using two core protocols, Arbitrum Rollup and Arbitrum AnyTrust. It has two primary chains: Arbitrum One and Arbitrum Nova. The ARB governance token is used to decentralize the governance of Arbitrum and its underlying protocols. It represents membership in the Arbitrum DAO and enables token holders to participate in the governance process by voting on proposals. Arbitrum's governance is driven by the Security Council and the Arbitrum DAO, a global community of ARB token holders and their delegates. This decentralized governance system ensures decisions align with the community's best interests.