Rework in the work

I think this post is or should be huge.
Well, the problem is huge so there's room for simple explanations and context.

I made minor fixes, then separated each part in two:
* "what X is" should be noob-friendly, clear and not be subject to change or discussion
   We should probably add links to the canonical docs.

* and "how I use X" which is where we can debate, with example code

What do you think? Let me know :)