Expert power derives from having knowledge that is valued by the organization or individuals with whom the person interacts. Expertise in a particular field or at problem solving or at performing critical tasks are types of expert power. Expert power is personal to the individual who has the expertise, hence it is different from the other three sources of power previously mentioned. However, the possession of expert power may be the basis for rising to a management position in the area of the expertise, now providing the incumbent with expert power as well that legitimate, reward and coercive power.
Referent power results when the individual engenders admiration, loyalty and emulation to the extent that the person gains the power to influence other. Charismatic leaders have referent power. They have a vision for the organization that they lead, strong convictions about the correctness of the vision, and great confidence in their ability to realize the vision, and are perceived by their followers as agents of change.
Connection power is more commonly referred to as "networking" these days. It is who you know, vertically and horizontally, both within and outside the organization. This may be referred to in some circles as the "Old Boys Club" and represents many of the political dynamics that make up organizations.
Information power is a power that can be either personal or positional. A manager should have more information power than his or her direct reports but it isn't always the case. As a result, an individual that is actively involved in the "grapevine" often has more accurate information than the manager. The "grapevine" is thought to be primarily rumor but, when studied, the "grapevine" has proven to be about 80% correct. Therefore, the person in the organization with the most reliable information is thought to have quite a bit of power.