The document describes Apache Sling, an OSGi-based application framework for building RESTful web applications on top of a content repository. It uses Apache Sling to build a sample coffee shop ordering application called Slingbucks. The application is built with only a few hundred lines of Java code and uses content to define things like coffee options and styles rather than hardcoding them. Apache Sling promotes the principle that "everything is content" and enables building full-featured applications with relatively little code by leveraging out-of-the-box HTTP services and the ability to extend functionality through OSGi plugins.