What is leadership?

I am in search of the definition of leadership and what does it mean to be a leader?
I will post my understanding of leadership and refer to the link I found
Leaders use common sense
Leaders know their strengths and weaknesses.
Leaders know others strengths and weaknesses
Leaders know that they are human and that they have limitations
Leaders accept the reality
Leaders can impersonate - think like some body else
Leaders have set of values that they believe
Leaders can anticipate the situation and visualize the situation
Leaders anticipate and adopt change quickly
Leaders initiate change
Leaders ask basic questions
Leaders challenge basics
Leaders value others values
Leaders get motivation from within
Leaders share ideas with everyone
Leaders keep their eyes & ears open to look for opportunities
Leaders touch the heart
Leaders Walk their talk
Leaders believe in teamwork and collaboration
Leaders believe in continuous improvement
Leaders understand our human emotions and reactions
Leaders have detachment
Leaders believe in balance, Fun, creativity

I found the following web site very interesting
http://theleadershipcircle.com/site/main/profile.htm