1. Concept
   1. software element
   2. relation among them
2. Purpose
   1. reducing software complexity
      1. abstraction
      2. separation of concerns
3. Documentation
   1. facilitate communication
   2. reuse
4. How
   1. a mix of art and science
5. Views
   1. Functional/logic view
   2. Code/module view
   3. Development/structural view
   4. Concurrency/process/runtime/thread view
   5. Physical/deployment/install view
   6. User action/feedback view
   7. Data view/data model
   8. etc
6. architectural styles and patterns
   1. Blackboard
   2. Pipes and filters
   3. Plug-in
   4. Peer-to-peer
   5. Event-driven
   6. etc