Optimism is an ecosystem of scalability solutions for the Ethereum blockchain. The main blockchain is the OP Mainnet, a layer 2 network based on Optimistic Rollup technology that enhances Ethereum's capacity while offering lower transaction fees. The Optimism teams also provide the OP Stack, a set of development tools that facilitate the creation of OP Chains, blockchains based on Optimism technology that form the Superchain, a galaxy of interconnected and interoperable blockchains.