Who is a hacker ?

Schneier well explains who a hacker is. Excerpt --
A hacker is someone who thinks outside the box. It's someone who discards conventional wisdom, and does something else instead. It's someone who looks at the edge and wonders what's beyond. It's someone who sees a set of rules and wonders what happens if you don't follow them. A hacker is someone who experiments with the limitations of systems for intellectual curiosity.
I think the most referenced explanation for the term Hacker is Eric S Raymond's "How to Become a Hacker"