Everything is iterative

1. Understand the Problem
2. Define the Requirements
3. Requirements Review
4. Develop a conceptual design (highest-level) & identify high risk elements
5. Conceptual Design review. Evaluate pros and cons of various approaches. Choose the one preferred design. Present a test plan.
5. Prototype/analyze the high risk elements.
6. Develop a complete, but preliminary design.
7. PDR
8. Finish the design.
9. CDR
10. Build it.
11. Test it.
12. Factory acceptance test (prove that it meets the requirements)