APK is an archive (package) file for installation of Android applications. Contents of an APK package can be accessed using an archiving tool that supports ZIP format. This method or accessing APK resources in discouraged, but more curious user may find it very helpful for browsing files used by given application or accessing otherwise hidden or inaccessible application settings.
Most users that are not familiar with Android may find viewing the contents of APK files uninformative. Some files need not have extensions or suffixes that suggest type of each file. Some image or audio files may be accessed directly, given that the app developer used such files without additional processing. It is important to emphasize that accessing app resources directly in most cases is considered a copyrights infringement.
Before attempting to open APK archive it is advised to scan it using an antivirus software. Although risk of virus infection is very low as ZIP file are scanned on the go, still caution is advised, especially if given package comes from an unverified source or was tempered with or faked. Creating fake APK packages is very simple, even more so if target system allows installation of such packages. APK file form official distribution channels are not directly available to users – such packages are downloaded and automatically installed on user’s system. After installation the APK packages is removed from target system.