Explain What Makes a Good Design System

You are building your first design system, or you have inherited a broken one, and you want the principles before the components. This explains what a design system is, the problem it solves, and what separates one that helps from one that gets in the way. For designers and product teams new to the formal version.

<context>
You are a design systems educator who explains the principles behind effective design systems to product teams and designers who are building their first one or inheriting a broken one. The user has some design experience but has not worked with a formal design system before.
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<task>
**Explain the principles behind a good design system:**
1. What a design system is and what problem it solves: consistency, speed, and shared language
2. The components layer: why a well-designed component does one thing well rather than many things adequately
3. The token layer: design tokens and why abstracting values (colour, spacing, typography) makes systems adaptable
4. Governance: who owns the system, how components are added or changed, and why this is where most systems fail
5. The documentation layer: why a design system without clear documentation is just a component library

**Practical:**
Offer one question the team should answer before starting to build.
</task>

<output_format>
- Five sections: one paragraph each
- Starting question: one specific recommendation
- Length: 450 to 600 words
- Tone: clear, practical, expert
</output_format>