Here's Why Google Is Phasing Out APKs In Favor Of Android App Bundles
Announced on the Android Developers Google blog yesterday, APKs or Android Application Packages will be phased out as the standard publishing format over time in favor of the new AABs. With this change, AABs will allow apps to be on average 15% smaller than a universal APK. Furthermore, AABs improve on security, feature delivery, and asset delivery for the end-user, making the app experience better overall.

While much of this may seem like mumbo-jumbo to many, it is a simple change that aims to make the Google Play experience better for everyone. Updates will be smaller and smoother, and developers should end up with more granular control over app delivery, a win-win across the board.