Arbitrum is an optimistic rollup built on Ethereum. Arbitrum leverages a set of whitelisted validators to monitor validity of transaction data and state changes via a fraud proof mechanism with plans to transition to permissionless validation.
Arbitrum supports an ecosystem of DeFi protocols such as GMX, Radiant, Camelot, Trader Joe, and Vertex. Additionally, well-known DeFi protocols like Uniswap, Curve, Aave, and Balancer have deployed on Arbitrum as well.
Arbitrum offers a suite of blockchain solutions, such as Arbitrum Nova and Arbitrum Orbit, that cater to different application requirements.