Is APK an abbreviation for Android Package Kit? What about the file itself? Is it an archive such as ZIP where during install the installer extracts and copies the files onto the file system?
APK files are a variant of the JAR file format, which are built on the ZIP file format, with a .apk file extension.
APK (Android Package) file is a file format which is created by Google. This format is one of the group members of Executable Files (similar to EXE, MST, AIR).
APK file extension is in the Open Handset Alliance which is a mobile phone platform based on Linux. This file extension is especially created when using Google's Android SDK. APK files contain the code files, resource files and the AndroidManifest XML file extension. For more detail http://edugoing.com/qna/index.php?qa=14&qa_1=describe-the-apk-format#a171