This document discusses designing Apex REST services for integrating the Force.com platform with external systems. It provides an overview of Apex REST services, including their architecture, using inner classes to handle requests and responses, and routing multiple actions without using REST OPTIONS. Code samples are shown to demonstrate implementing an Apex REST handler class and routing actions. The presentation concludes with a recap of how Apex REST services allow integrating external systems through a REST API while controlling business processes rather than exposing the raw Force.com API.