Core Android Concepts: Activity lifecycle, Fragment usage, threading (AsyncTask, Coroutines, Executors), View Binding, etc. Frameworks and Libraries: Knowledge of Jetpack components (Room, Navigation, LiveData, etc.), dependency injection (Dagger/Hilt/Koin), and build tools (Gradle). UI/UX: Custom views, animations, and Material Design principles. Networking: REST APIs, Retrofit, WebSocket, and offline caching. Performance Optimization: Memory leaks, APK size reduction, app performance tuning. Security: Best practices for data storage, encryption, and authentication. Example Questions: How do you handle configuration changes in Android? Explain the difference between Service and IntentService. How would you optimize app startup time?