Dink Smallwood video
If you want to install an application on Windows, we have an .exe file for that. For Mac OS X, we have .dmg files. Those of you who come from Symbian and Java phones background must be knowing about the .sis, .sisx and .jar files. In the same way way, have a specific file format for Android smartphones that is used to install application on it and it is called an APK file (because it has the extension of .apk)
Why would I want to install an APK File? Searching for and downloading APK files allows you to access apps that have leaked ahead of their official release. (You can also download apps which have been banned, though we would not recommend this.) APK files of new Android builds are often leaked ahead of time, giving you early access to all the exciting new features that otherwise wouldn’t be available to you. A recent example of this would be with the early Android L build which found its way online despite that it’s yet to be officially released.
First of all, we will have to enable the option to install the applications from unknown source on our Android. Open your Android system settings and click on Applications (Programs for some of the HTC devices) and check the option Unknown source. Those of you who are on Android ICS 4.0 you will find these settings under the security settings. On most of the devices, you can now simply click on the file using any of the file managers to install them, using the built-in package manager. If your device does not have a package installer by default, you can download and install an APK installer application from Google Play.
When you want to install an APK manually, just open the APK installer app and navigate to the folder where you have your APK files saved. Now, simply click on the application to bring on the installation screen. Click the install button to successfully install the application.