The document discusses ExpressionEngine and how it can be used to rapidly develop sites using templates, addons, and other tools. It introduces the EE Sandbox approach, which involves setting up templates, addons, global variables and other site elements as reusable components. This allows developers to quickly build out new sites using the same patterns. The document provides an overview of the key elements in an EE Sandbox setup and demonstrates how to install the components, create templates, import assets and move the site to a new server.