To download one of the applications that are not on the Google Playstore, you need to know what an .apk file is and how to install it. 'APK' is an installation file format used to install a betting application or any other application or game on the Android operating system. Since you can find many sources on the Internet from which you can download .apk files, users are still advised to use the Google Playstore; if you do opt for any of these sources, be sure to keep them safe. You can easily check which sites are recommended for .apk files on the Internet.