Optimism

Optimism is designed around four core tenets:

• Simplicity
• Pragmatism
• Sustainability
• Optimism

Optimism aims for the minimum number of moving parts while building a layer-two solution for Ethereum. In practice, this means using proven Ethereum code and infrastructure when possible. Optimism thus aims to keep its code as simple as possible and work directly with existing codebases.

The ecosystem further emphasizes pragmatism and is driven by the real-world needs and constraints of its own team and the users engaging with the ecosystem. Hence, Optimism aims to build iteratively and implement features like EVM equivalence gradually.

Optimism's design process is built around the idea of long-term sustainability and not taking shortcuts to scalability. That is why it uses optimistic rollups and takes advantage of the consensus mechanism of Ethereum to scale the network. Blocks are constructed and executed on the L2 (Optimism), while user transactions are batched up and submitted to the L1 (Ethereum). The L2 has no mempool, and transactions are immediately accepted or rejected. This guarantees a smooth user experience while ensuring security through the Ethereum consensus mechanism.

Transactions are submitted to Ethereum without direct proof of validity and can be challenged for a certain period of time (currently seven days). After that, a transaction is considered final. That is why withdrawals from Optimism to Ethereum take seven days to complete.

Source : Coinmarketcap