Frequently alled with legitimate power is expert power. Over time a person may become expert in an area; for example, a congressperson may point out to a citizens' group a strategy that will be carefully sonsidered, because he or she is seen both as an ally though his or her legitimate power and as an expert familiar with the machinations of Congress. Exper power may also exist independent of position. It is based on the person's specialized knowledge, information, or skill.