Legitiment Power

Legitimate power is the power that comes with a formal position of leadership.   Your professor, for instance, has the legitimate power associated with being a professor.
Related to legitimate power is coercive power—the ability to mete out punishment for bad behavior—and reward power—the ability to reward good behavior.   For instance, your professor has the ability to give good grades (reward power) as well as bad grades (coercive power) depending upon the quality of your work (work hard! ).
 Expert power is the power one wields because of expertise and knowledge in a particular area.   This can either undermine or strengthen legitimate power.   For instance, if a professor is teaching a biology class but has a PhD in business, her expert power will be minimized!   Likewise, one can accrue expert power even if one doesn’t have legitimate power.   By working hard and making sure you know the ins and outs of your job, you can be a blessing to your superiors and co-workers, thereby gaining expert power and influence.
 Referent power is the power gained by being able to work well with people and relate to them in meaningful and authentic ways.   It is closely related to “emotional intelligence”.   Ultimately, referent power is the most important power to possess because it can either affirm or undermine the other types of power.   If a leader is an arrogant jerk, people will not want to work with him.   The leader can punish and punish (i.e. “The beatings will continue until morale improves”), but in the end, productivity will decrease because of lowered morale, no matter how smart the leader is or the position the leader holds in the organization.   On the other hand, if the leader is humble, cares for employees and knows how to make people feel comfortable and supported on the job, employees will be more willing to work for that leader.   As the saying goes, “people don’t care what you know until they know that you care.”
 Of all of the powers listed above, referent power...