# Structure: describing and drawing a system

How the structure of a running system is written down and drawn, for readers who come with one question each. The
shapes are the [architecture description](../../shapes/architecture-description.md) and the
[system diagram](../../shapes/system-diagram.md).

| Principle | Claim |
|---|---|
| [Order a description by the reader's questions](by-the-readers-questions.md) | readers, context, parts, invariants, runtime, deployment, reasons |
| [Every diagram has a key, every arrow a label](diagram-key-and-labels.md) | a key under each diagram, a label on each arrow |