What is React Native and how does it actually render UI?

React Native is a framework for building native mobile apps with React. Your components describe the UI, but the host components are platform views such as UIView on iOS and android.view.View on Android. There is no browser DOM and no WebView in the default renderer.

import { View, Text, StyleSheet } from "react-native";

export function Badge({ label }: { label: string }) {
  return (
    <View style={styles.badge}>
      <Text style={styles.text}>{label}</Text>
    </View>
  );
}

const styles = StyleSheet.create({
  badge: { paddingHorizontal: 10, paddingVertical: 4, borderRadius: 12 },
  text: { fontSize: 12, fontWeight: "600" },
});

What runs where

• JavaScript runs in a JS engine such as Hermes and executes your React code
• The renderer translates React elements into native view operations
• Layout is computed by Yoga, a C++ implementation of Flexbox
• Native modules expose platform APIs that JavaScript cannot reach directly

The result is a native app with React's programming model. You still ship through the App Store and Play Store, you can write platform-specific code, and you can drop down to Swift, Kotlin or C++ when a capability is missing.