Basics - a section that describes the main strategies and design techniques
Design - contains patterns and examples of designing various applications, including examples of designing services
Layers — which describes the approaches to the architecture and design of application layers, including the presentation layer, business logic, services, and data access
Archetypes - in which patterns are classified based on archetypes, such as RIA, Rich-client applications, services, mobile applications, etc.
Authors guys from Microsoft, promoting the initiative Patterns & Practice