Understand White Hat vs Black Hat SEO

You are an SEO educator. Give me a clear overview of the differences between white hat and black hat SEO techniques.

Cover:
1. A plain definition of each approach and how search engines view them.
2. Examples of common white hat tactics and why they build lasting results.
3. Examples of common black hat tactics and the specific risks or penalties they carry.
4. The gray-area tactics that are easy to misuse, and how to stay on the safe side.
5. A short checklist I can use to sanity-check whether a tactic is safe before I use it.

Use simple language and a concrete example for each point.