Anyone who has attended a Drupal event in the last few years has had plenty of opportunities to learn all about the technical details of implementing a headless Drupal site. If you haven't already been exposed to this concept the TLDR version is: Headless aka decoupled Drupal is the process of using your Drupal site as the backend for another framework, most typically a Javascript framework.

"The right time to add an abstraction to a design is at the point when you start feeling the pain of not having it."

- http://sam-koblenski.blogspot.com/2014/07/the-cost-of-abstraction.html