The Optimism chain is a Layer 2 scaling solution for the Ethereum blockchain. It is designed to improve transaction speed and reduce costs while maintaining security and decentralization. Optimism achieves this by using Optimistic Rollups, a technology that processes transactions off-chain and periodically submits summaries to the Ethereum mainnet.

Transactions are executed off-chain and bundled (rolled up) into batches.
These batches are submitted to Ethereum with a commitment, significantly reducing gas fees and increasing throughput.
Security through Fraud Proofs:

Optimism assumes transactions are valid ("optimistically") but allows users to challenge incorrect transactions using fraud proofs within a specified dispute period.
This ensures the security is anchored to Ethereum’s robust consensus mechanism.

Optimism is fully compatible with the Ethereum Virtual Machine (EVM), making it easy for developers to port their Ethereum-based decentralized applications (dApps) without significant changes.

By rolling up multiple transactions into one batch, Optimism drastically reduces the gas fees compared to processing individual transactions on Ethereum.
Open Governance:

Optimism is governed by the Optimism Collective, a community-driven governance model that includes mechanisms for retroactive public goods funding.