Usually, when you have to install a new app in your Android device then you can launch the Google Play store and search for the app and install it from there. You can also browse the Google Play store website in the browser, look up apps and install the ones you want. But sometimes, you get apps in form of the APK files not available on Google Play store. For example, some of the CDs that come with computer magazines have Android apps in APK format. If you copy these APK files to the SD card and try to open them in your Android device, it refuses to install them and shows a message that “Install Blocked – For security, your phone is set to block installation of apps from unknown resources.”
This is actually a great setting to prevent you from installing rogue or harmful apps in Android. But if you are using a security solution like Bitdefender Antivirus Free for Android, then you no longer have to worry about such malicious apps.
If you want to install the app from a APK file anyway, then you have to open the Android settings either from the settings icon in the Android Apps section or by tapping on Settings in the Install Blocked message. In the Settings menu, you have to open the Security settings.
In the Security settings, scroll down and you would see a setting labeled Unknown sources. You have to place a checkmark against this settings to allow installation of apps from unknown sources.
A message will popup informing you about the risks of installing apps from unknown resources and how your personal data is vulnerable to attack from such apps. You can tap on OK to proceed and make the changes.
That’s it. From now you will be able to install apps that are available in form of APK files. But at the same time, you should always try to install apps from reputed trustworthy sources like Google Play store. The APK files should be used to install only if very much necessary.