First opens Activity: onCreate(),OnStart(),onResume() User Clicks backButton(): onPause(),onStop(),onDestroy() Navigating to another screen: First Screen:: onPause(),onStop() Second Screen: onCreate(),OnStart(),onResume() Presses Backbutton in Activity2: Second Screen: onPause(),onStop() ,onDestroy() First Screen: onRestart(), onStart(), onResume() User locks the device: onPause(),onStop() Again Opens lock: onRestart(), onStart(), onResume()