The document discusses building RESTful web services with PHP. It defines REST and RESTful services as being resource-oriented rather than protocol-based. It explains how PHP supports REST through features like $_SERVER variables to access HTTP request details and $_POST/$_GET to access form data. The document then describes the author's own RESTful framework in PHP, which defines resources as classes that handle different HTTP methods, generates URIs for resources, and supports multiple MIME types and views. It provides examples of resource and composite resource URI patterns as well as handling MIME types based on the HTTP Accept header.