How do we plan, design, write, and test code well?

The pragmatic nuts-and-bolts approach to creating systems. If you want to wonder, wonder this: Have you REALLY UNDERSTOOD every single word in the problem you are trying to solve? What is a good system diagram do? What does well-designed software look like? Why is pseudocode important to software development? What is clean code? What are right tests to use?

Good development leads to good products. Show how you can apply your understanding and skill in good development to any software problem.