Maybe someone has an official answer, but I always thought of front-end as anything in the browser and back-end as anything on the server. Front-facing is user-

Maybe someone has an official answer, but I always thought of front-end as anything in the browser and back-end as anything on the server. Front-facing is user-facing. Back-facing is hidden plumbing. The article seems to be more about UI vs. non-UI code. Rather than have part of the UI code in the business logic, it can be split out. This was already possible, but with Node.js you can have the server-side half of the UI code be in Javascript so all the UI code is Javascript and the business logic code can be in some other language.