Modularizing Android Applications is fun

Single module android applications — at some point in our Android development career it’s likely we’ve worked on, or are working on, a project that consists of a single module. Now, there’s nothing wrong with that at all and in a lot of cases, a single module will most likely do the job.

But in cases where our applications may grow, or we may want to take advantage of new distribution features (Instant apps, app bundles) from Google, or even just create a clear separation of concerns to make our project easier to work with— modularizing our applications can help us to achieve all of these things. 

https://medium.com/google-developer-experts/modularizing-android-applications-9e2d18f244a0