File with a .DEX extension contains a complex executive file, for instance, translated from a complex Java program – a part of an Android application. Many DEX files are compressed into a ZIP archive and constitute a package with an .APK file extension, which is a final application for Android.

DEX files can be created manually or automatically on the basis of existing elements of programs for mobile devices. The created by Google Android system is based on Linux, while the DEX files are interpreted by the virtual machine called Dalvik, they are called Dalvik Executables.