Arbitrum is a layer 2 scaling solution for Ethereum, which was launched in May 2021. Here is a brief history of Arbitrum:

• 2018: Offchain Labs, the company behind Arbitrum, is founded by Ed Felten, Steven Goldfeder, and Harry Kalodner, with the goal of creating a more scalable and efficient blockchain infrastructure.

• 2019: Offchain Labs raises $3.7 million in seed funding to develop its blockchain scaling technology.

• 2020: Offchain Labs releases a whitepaper outlining the design and architecture of Arbitrum, which is described as a "trustless, general-purpose, scalable, and low-cost" layer 2 solution for Ethereum.

• May 2021: Arbitrum is launched on Ethereum mainnet, allowing users to deploy smart contracts and interact with decentralized applications (dapps) on Arbitrum's more scalable and efficient infrastructure.

• August 2021: Arbitrum reaches a total value locked (TVL) of over $1 billion, as more users and dapps migrate to the platform to take advantage of its scalability and low gas fees.

Today, Arbitrum is one of the leading layer 2 scaling solutions for Ethereum, with a growing ecosystem of dapps and users. The platform is designed to be highly compatible with existing Ethereum infrastructure, making it easy for developers to migrate their dapps to Arbitrum and take advantage of its scalability benefits. The team behind Arbitrum continues to work on improving the platform and adding new features, such as support for cross-chain interoperability and other scaling solutions.