What is Optimism op?

Could you please elaborate on what Optimism OP actually is? I'm quite curious about its functionalities and how it fits into the larger cryptocurrency and blockchain ecosystem. Could you explain its role in facilitating transactions and enhancing scalability? Also, how does it differ from other solutions in the market? Is it a layer-two solution? If so, how does it work in conjunction with the Ethereum blockchain? Furthermore, what are the benefits of using Optimism OP for developers and end-users alike? I'm eager to learn more about its potential and how it could revolutionize the crypto space.