According to Wikipedia, Leadership is both a research area and a practical skill encompassing the ability of an individual or organization to "lead" or guide other individuals, teams, or entire organizations. Leadership is the art of motivating a group of people to act toward achieving a common goal.
One can be identified as a good or bad leader depending on 3 qualities they possess and the impact made on their followers.
Important skills or attributes a leader must possess
Team building and management
Delegating duties appropriately
A good leader has the all the skills mentioned above and uses it to inspire his followers and subordinates. He listens to advice and acts on them.