By definition, power is the ability to influence the behavior of others to get what you want. According to Bauer and Erdogan (2009), there are six sources of power:

• Legitimate power is power that comes from one’s organizational role or position. For example, a manager can assign tasks to his subordinates, a policeman can arrest a citizen, and a teacher assigns grades to his students. Others comply with the requests these individuals make because they accept the legitimacy of the position, whether they like or agree with the request or not.
• Reward power is the ability to grant a reward, such as an increase in pay, a perk, or an attractive job assignment. Reward power tends to accompany legitimate power and is highest when the reward is scarce. Anyone can have reward power in the form of public praise or giving someone something in exchange for their compliance.
• Coercive power is the ability to take something away or punish someone for noncompliance. Coercive power often works through fear, and it forces people to do something that ordinarily they would not choose to do. The most extreme example of coercion is government dictators who threaten physical harm for noncompliance.
• Expert power comes from knowledge and skills. Technology companies are often characterized by expert, rather than legitimate power.
• Information power comes from the ability to access to specific information. For example, knowing price information gives a person information power during negotiations. In organizations, a person’s social network can either isolate them from information power or serve to create it.
• Referent power comes from the personal characteristics of the person such as the degree to which we like, respect, and want to be like them. Referent power is often called charisma—the ability to attract others, win their admiration, and hold them spellbound.

Legitimate, Reward, Coercive and Information power can be categorized as “organizational bases of power”, which are derived from organizational position and organizational policies. On the other hand, Expert and Reference power are “personal bases of power”, which are derived from personal characteristics.

Reference:
Bauer, T. and Erdogan, B., 2009. Organizational Behavior. 1st ed. Flat World Knowledge, Inc.