Explain

Goal: the user understands the thing well enough to change it or decide about it. Not a lecture. Not a tour of everything.

1. Find the level

Use what you already know about the user (their questions, their code, their role). If you do not know, assume a smart person who is new to this exact topic. Do not ask about level unless the answer would change a lot.

2. Write in layers

Stop at the layer that answers the question. The user can ask for more.