An Android app is of APK file type, which is sometimes useful yet not so useful because of its limitations.

A ​modified apk or a mod apk is the same app altered by a developer to gain access to add, remove or unlock some hidden features. For example this ​popular Google Camera APK that is also a mod apk.

Usually these types of modifications bring paid apps for free, unlimited resources in games etc. Because of these features, the Mod APKs are more useful than a normal app.

In this book I am trying to introduce how this works and how you can get the taste of this.

You can visit this mod apk site that has a lot of such modded apps and games. you can download any familiar app and install it on your phone to see the difference between the original and a mod.