Most of us Android phone users keep installing and trying different applications and games from the Google Play store on a regular basis. These applications are installed automatically and just appear on our phones when we click the install button. However, there is another way to install applications and games, and even live wallpaper on your phone without using an application store like Google Play. That's where APK or Android application package files come into play.
Anyone who has used an Android phone and likes to install lots of applications and games will likely have heard or read about APK files. The APK file extension is a special file format that works much like a standard EXE or executable file does on a Windows computer. It is an executable program file that installs an application on your Android smartphone.
These files are very easy to use but you first need to set up your phone to install applications from third-party sources. There's an option for that in your phone's settings, usually found in the security or applications settings sections. Once you check that, you only need to copy an APK file to your memory card, and you're good to go.
However, the tricky part is finding a reliable source for these files. You can not just download files with the APK file extension from any website. Quite a few websites that do not run proper antivirus checks and verify the application files uploaded there. Some of these can easily be viruses or other malware designed to give someone else access to your phone's features like the camera, microphone, your picture gallery and contacts lists, breaching your privacy. As long as you download APK files from reliable sources though, you should not have any problems.
Most of the time, you'll find discontinued applications or live wallpapers like Flappy Bird online in the form of APK files that other users of the app have uploaded to websites. They are a very good source of custom applications as well that users made for their own use. Those simple, small, and mostly ad free applications are great to add some new features to your phone such as a flashlight or an RSS reader. However, one should be very careful about what file we download and from where because not everyone can make good quality applications and some can even mess up the phone if run on an incompatible device.