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Turbo Modules are the next-generation native module system in React Native's New Architecture, replacing the traditional bridge-based modules. They use the JavaScript Interface (JSI) for direct, synchronous communication between JavaScript and native code, eliminating the serialization overhead of the old JSON bridge. Turbo Modules also support lazy loading — they're only initialized when first accessed rather than at app startup, which significantly improves launch performance.

The React Native New Architecture is a fundamental rewrite of React Native's internals, replacing the asynchronous bridge with a JavaScript Interface (JSI) that enables direct, synchronous communication between JavaScript and native code. It consists of three pillars: Fabric (a new rendering system), Turbo Modules (a faster native module system), and Codegen (automatic type-safe native code generation from JS specs). This architecture significantly improves performance, reduces startup time, and enables concurrent rendering features from React 18.

Hermes is an open-source JavaScript engine developed by Meta, optimized specifically for running React Native applications on mobile devices. It uses ahead-of-time (AOT) compilation to convert JavaScript into bytecode during the build process, resulting in faster app startup times, reduced memory usage, and smaller app sizes compared to JavaScriptCore. Hermes is now the default JavaScript engine for React Native and also supports iOS since React Native 0.70.

A WebView is an embeddable browser component that renders web content (HTML, CSS, JavaScript) inside a native mobile application. It allows developers to reuse existing web code within a native app shell, commonly used for displaying rich content, integrating web-based features, or building hybrid apps. While convenient, WebView-heavy apps typically have worse performance and a less native feel compared to truly native or React Native/Flutter approaches.

Styled Components is a popular CSS-in-JS library for React and React Native that uses tagged template literals to style components. It automatically generates unique class names, supports dynamic styling based on props, handles vendor prefixing, and provides full theming capabilities. The library colocates styles with components, making it easy to understand what each component looks like and to delete styles safely when removing components.

Expo is a platform and set of tools built around React Native that simplifies mobile app development by providing a managed workflow, pre-configured native modules, and over-the-air update capabilities. With Expo, you can start building without installing Xcode or Android Studio, test on physical devices via the Expo Go app, and deploy updates without app store review cycles. Expo's EAS (Expo Application Services) handles cloud builds, submissions, and updates for production apps.