Optimism is a layer-2 solution designed to improve the scalability and efficiency of the Ethereum blockchain. It utilises a technique called optimistic rollups to enable faster and cheaper transactions while still leveraging the security of the Ethereum mainnet.

Optimistic rollups work by processing transactions off-chain in an optimistic manner and submitting a summary of those transactions to the Ethereum mainnet. This approach allows for a higher throughput and lower transaction fees compared to directly executing transactions on the Ethereum mainnet. Additionally, it maintains the security of Ethereum by relying on the mainnet’s consensus mechanism.