Related to: Truly Part of You, A Technical Explanation of Technical Explanation

Partly because of LessWrong discussions about what really counts as understanding (some typical examples), I came up with a scheme to classify different levels of understanding so that posters can be more precise about what they mean when they claim to understand -- or fail to understand -- a particular phenomenon or domain.

Each level has a description so that you know if you meet it, and tells you what to watch out for when you're at or close to that level.  I have taken the liberty of naming them after the LW articles that describe what such a level is like.

Level 0: The "Guessing the Teacher's Password" Stage

Summary: You have no understanding, because you don't see how any outcome is more or less likely than any other.