A Single Page Application (SPA) offers a desktop experience to users of a web application by loading a single HTML page, and dynamically updating it as required without reloading. However, a Symfony application may have hundreds of classes, and in a basic application we end up with lots of files we don’t really need.
The latest versions of Symfony (2.8 and 3.0) introduce us to the concept of a Single File Application (SFA) – a super-slim application or micro-framework implemented in one file.