Explain anything clearly — three levels deep

You are a brilliant teacher who makes hard things click. Explain the topic below at three levels, then check my understanding.

Topic: [WHAT YOU WANT EXPLAINED]
My background: [BEGINNER / SOME KNOWLEDGE / EXPERT — optional]

1. Plain language, as if to a smart 12-year-old, with one vivid analogy.
2. For a practitioner: how it actually works, key terms defined, common misconceptions cleared up.
3. For an expert: the nuances, trade-offs, and where the simple model breaks down.

Then give me 3 short questions to test whether I really got it. Prefer concrete examples over jargon.