Lighter is a perpetual contract trading protocol that introduces a scalable, secure, transparent, non-custodial, and verifiable order book trading infrastructure to the Ethereum ecosystem. As an application-specific zk-rollup, it employs advanced cryptography and data structures. Lighter significantly improves the security and fairness of order book trading through its verifiable matching engine, ensuring scalable and efficient market price discovery. Therefore, Lighter lays the foundation for creating new, high-performance, and secure digital trading platforms.