Basic Information Concerning APK Applications. Smart phones currently nowadays have become very popular and come with a variety of operating systems such as windows, Mac or Android. The most popular is the android. Many mobile phone manufacturers can install android applications in their gadgets since it is an open source platform. Mobile phones, therefore, have become cheap to manufacture since an OS is already available. Various apps are coming up every day, but the most common ones are the android apps. Each of the application when complete can carry different files and folders. The features of an app are determined by the files and folders it carries. In order for a mobile app to function, an archive with all the necessities is required first. Android package kit is the term used for the archive file. Runnning an app in a mobile phone requires some special data and files that are found in an android package kit. The functions and abilities of an application is contained in the source code. The other name for the source code is the classes.index. Manifest file is the other component of the APK. The component provides specifications for permission to the application’s needs, package, it’s flow, signatures, certificates, version codes and SHA-1 Digest. The other component is referred to as libs. This is a directory that compiles codes or jar files used as the library for the application. Texts, audios, and fonts are stored in the APK component known as the asset. The resources component is the element which defines the layout for the various pages of the app. Other components of the android application package are META-INF and res directories. Testing of an application has to be carried out during development. The developers of the app generate an export app where they sign in the application with secret code. The purpose for that is to enhance authenticity. Uploading of the app in to the Google play store is done to allow users download it. The APK is the one that is downloaded and installed on the phone when one requests the app from play store. Aside from the Google play store, the other platform that offers android applications for free without requiring an account is the APK MIRROR. Applications found in Google play store can be downloaded in the APK MIRROR. Having an account is not a requirement when one is using APK MIRROR to download android apps. Security measures have been put in place by both APK MIRROR and Google to ensure that only original and trusted apps are made available to customers. The High-security measures include signature authorization and verification of certificates. APK MIRROR offers the ability to download older versions of an app if one is not satisfied with new one.