The document discusses the Struts framework and the Tiles plugin. It provides an overview of Struts, describing its main objects and MVC architecture. It then explains what a plugin is and how it can be used to extend Struts functionality. Specifically, it details how the Tiles plugin addresses limitations of including layouts across pages by defining templates that can be reused. It provides an example of configuring and using the Tiles plugin with Struts to define page layouts, headers, footers and dynamic content in a modular way.