Hermes is a JavaScript engine optimized for React Native, introduced by Meta in 2019, that has fundamentally transformed how React Native applications are compiled and executed on devices. By shifting from JavaScriptCore's (JSC) just-in-time (JIT) compilation to an ahead-of-time (AOT) compilation strategy, Hermes enhances performance significantly, reducing load times and memory usage for applications like Facebook Marketplace. Hermes improves the development and user experience by moving most processes to build time, optimizing bytecode for devices, and introducing the Hades garbage collector that runs concurrently with the main interpreter thread, minimizing application freezes. Despite some initial limitations in supporting ECMAScript 2015 features, most have been addressed, making Hermes widely adopted within the React Native community and enabling React Native to better compete with native frameworks like Swift and Kotlin.