For Android 4.0 and above: Go to Settings > Security > Unknown Sources > Toggle ON.
This is the critical part. The internet is littered with malware disguised as "Viber for Android 2.3.3." If you are searching for a feature about downloading APKs, you must follow the : Download APK File - Android 2.3.3 and up
Q: Can I update apps using APK files? A: Yes, APK files can be used to update apps on your device manually. For Android 4
: Minimal background processes, preserving battery life on aging hardware. Cons: Unknown Sources >
By manually downloading an APK file, you can install apps that are no longer available on the Play Store for your specific Android version, especially if you are running or higher.
