This article applies to Android applications in Windows using IntelliJ IDEA development tools. Windows 7 was used in this example but the explanation will work for other recent versions of Windows. It is quite a task learning how to use mobile application development tools. This page describes how to digitally sign your .apk file which is the Android application package file. In short, your Android program file. Once you have created an APK file to launch it, simply copy to your device and use the Android file manager to install it. The picture below shows the digital signature keystore file, the unsigned APK file and the signed APK file. The procedure of signing the APK file is quite straighforward but first you must ensure your Java JDK is properly installed and that the Java tools are accessible on your commandline (Windows command console - what used to be called the DOS window). Most important is that your PATH environmental variable (In Windows 7 find this at: Control