Complex Concept ELI5

Explain {CONCEPT} to a 5-year-old (or layperson).

Complexity level: {LEVEL}
Analogy preference: {ANALOGY_TYPE} (e.g., cooking, cars, lego)

Provide:
1. The one-sentence simple explanation
2. The "Lego/Analogy" explanation
3. Why it matters (real world application)
4. Key terms simplified