Explain Like I'm a Beginner

Explain {{concept}} to someone who has never encountered it before.

Rules:
- Start with a one-sentence definition a 12-year-old would understand
- Use a real-world analogy to make it concrete
- Then build up to the technical details in 3 levels:
  Level 1: The basic idea (no jargon)
  Level 2: How it actually works (introduce key terms, define each one)
  Level 3: Why it matters and how it's used in practice
- End with: "You'd use this when..." followed by 3 real scenarios

Total length: {{length}} (options: brief = 200 words, standard = 500 words, deep dive = 1000 words)