WHAT'S THE MEANING
An APK (Android Application Package) file is a file format that is used to distribute and install applications on Google's Android operating system. Mod APKs or Modified APKs are basically cracked apps that have had their additional features unlocked that would otherwise not be possible without having to pay for them first.
DID YOU KNOW?
As of the third quarter of 2018, the Google Play Store has made approximately 2.1 million apps available to its users. That is a little more than Apple's own App Store which sits at 2 million apps. Both platforms have come a long way since the introduction of their respective Application Stores which was on July 10, 2008, for Apple's iOS and March 11, 2015, for Google's Android operating systems.
The question now is why do so many people resort to using modded APKs from APK download sites in the first place. Simply put, no one wants to pay for something if they can get it for free. Things are not all roses though as using Modified APKs has its downsides as well. For one, since you did not acquire the app officially through the Play Store, Google does not officially recognize your app as being purchased by you. This will result in you not being able to avail of any future updates the app might have that fixes existing bugs or adding new content or features on top of what is already available. Google is aware of this practice and has made certain steps that might somehow discourage this behavior by implementing a "try before you buy" model with some of its more popular apps. This move would give its users a bit more freedom to try the apps first and then purchase it if they are satisfied with what they are getting."